diff --git a/annotations/src/main/resources/revisions/Bullet/0.json b/annotations/src/main/resources/revisions/Bullet/0.json
index 4904375b03..f9e8a830d5 100644
--- a/annotations/src/main/resources/revisions/Bullet/0.json
+++ b/annotations/src/main/resources/revisions/Bullet/0.json
@@ -1 +1 @@
-{fields:[{name:collided,type:arc.struct.IntSeq,size:-1},{name:damage,type:float,size:4},{name:data,type:java.lang.Object,size:-1},{name:lifetime,type:float,size:4},{name:owner,type:Entityc,size:-1},{name:team,type:mindustry.game.Team,size:-1},{name:time,type:float,size:4},{name:type,type:mindustry.entities.bullet.BulletType,size:-1},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
+{fields:[{name:collided,type:arc.struct.IntSeq,size:-1},{name:damage,type:float,size:4},{name:data,type:java.lang.Object,size:-1},{name:lifetime,type:float,size:4},{name:owner,type:mindustry.gen.Entityc,size:-1},{name:team,type:mindustry.game.Team,size:-1},{name:time,type:float,size:4},{name:type,type:mindustry.entities.bullet.BulletType,size:-1},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/Bullet/1.json b/annotations/src/main/resources/revisions/Bullet/1.json
deleted file mode 100644
index c2d8c52eb2..0000000000
--- a/annotations/src/main/resources/revisions/Bullet/1.json
+++ /dev/null
@@ -1 +0,0 @@
-{version:1,fields:[{name:collided,type:arc.struct.IntSeq,size:-1},{name:damage,type:float,size:4},{name:data,type:java.lang.Object,size:-1},{name:lifetime,type:float,size:4},{name:owner,type:mindustry.gen.Entityc,size:-1},{name:team,type:mindustry.game.Team,size:-1},{name:time,type:float,size:4},{name:type,type:mindustry.entities.bullet.BulletType,size:-1},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/Bullet/2.json b/annotations/src/main/resources/revisions/Bullet/2.json
deleted file mode 100644
index 04b1c437de..0000000000
--- a/annotations/src/main/resources/revisions/Bullet/2.json
+++ /dev/null
@@ -1 +0,0 @@
-{version:2,fields:[{name:collided,type:arc.struct.IntSeq,size:-1},{name:damage,type:float,size:4},{name:data,type:java.lang.Object,size:-1},{name:lifetime,type:float,size:4},{name:owner,type:Entityc,size:-1},{name:team,type:mindustry.game.Team,size:-1},{name:time,type:float,size:4},{name:type,type:mindustry.entities.bullet.BulletType,size:-1},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/Bullet/3.json b/annotations/src/main/resources/revisions/Bullet/3.json
deleted file mode 100644
index 30b9ec33cc..0000000000
--- a/annotations/src/main/resources/revisions/Bullet/3.json
+++ /dev/null
@@ -1 +0,0 @@
-{version:3,fields:[{name:collided,type:arc.struct.IntSeq,size:-1},{name:damage,type:float,size:4},{name:data,type:java.lang.Object,size:-1},{name:lifetime,type:float,size:4},{name:owner,type:mindustry.gen.Entityc,size:-1},{name:team,type:mindustry.game.Team,size:-1},{name:time,type:float,size:4},{name:type,type:mindustry.entities.bullet.BulletType,size:-1},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/EffectState/0.json b/annotations/src/main/resources/revisions/EffectState/0.json
index 5ce16bf09c..88eb281607 100644
--- a/annotations/src/main/resources/revisions/EffectState/0.json
+++ b/annotations/src/main/resources/revisions/EffectState/0.json
@@ -1 +1 @@
-{fields:[{name:color,type:arc.graphics.Color,size:-1},{name:data,type:java.lang.Object,size:-1},{name:effect,type:mindustry.entities.Effect,size:-1},{name:lifetime,type:float,size:4},{name:offsetX,type:float,size:4},{name:offsetY,type:float,size:4},{name:parent,type:Posc,size:-1},{name:rotation,type:float,size:4},{name:time,type:float,size:4},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
+{fields:[{name:color,type:arc.graphics.Color,size:-1},{name:data,type:java.lang.Object,size:-1},{name:effect,type:mindustry.entities.Effect,size:-1},{name:lifetime,type:float,size:4},{name:offsetX,type:float,size:4},{name:offsetY,type:float,size:4},{name:parent,type:mindustry.gen.Posc,size:-1},{name:rotation,type:float,size:4},{name:time,type:float,size:4},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/EffectState/1.json b/annotations/src/main/resources/revisions/EffectState/1.json
deleted file mode 100644
index 0ccd683257..0000000000
--- a/annotations/src/main/resources/revisions/EffectState/1.json
+++ /dev/null
@@ -1 +0,0 @@
-{version:1,fields:[{name:color,type:arc.graphics.Color,size:-1},{name:data,type:java.lang.Object,size:-1},{name:effect,type:mindustry.entities.Effect,size:-1},{name:lifetime,type:float,size:4},{name:offsetX,type:float,size:4},{name:offsetY,type:float,size:4},{name:parent,type:mindustry.gen.Posc,size:-1},{name:rotation,type:float,size:4},{name:time,type:float,size:4},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/EffectState/2.json b/annotations/src/main/resources/revisions/EffectState/2.json
deleted file mode 100644
index fb05e5f923..0000000000
--- a/annotations/src/main/resources/revisions/EffectState/2.json
+++ /dev/null
@@ -1 +0,0 @@
-{version:2,fields:[{name:color,type:arc.graphics.Color,size:-1},{name:data,type:java.lang.Object,size:-1},{name:effect,type:mindustry.entities.Effect,size:-1},{name:lifetime,type:float,size:4},{name:offsetX,type:float,size:4},{name:offsetY,type:float,size:4},{name:parent,type:Posc,size:-1},{name:rotation,type:float,size:4},{name:time,type:float,size:4},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/EffectState/3.json b/annotations/src/main/resources/revisions/EffectState/3.json
deleted file mode 100644
index 41991e73c4..0000000000
--- a/annotations/src/main/resources/revisions/EffectState/3.json
+++ /dev/null
@@ -1 +0,0 @@
-{version:3,fields:[{name:color,type:arc.graphics.Color,size:-1},{name:data,type:java.lang.Object,size:-1},{name:effect,type:mindustry.entities.Effect,size:-1},{name:lifetime,type:float,size:4},{name:offsetX,type:float,size:4},{name:offsetY,type:float,size:4},{name:parent,type:mindustry.gen.Posc,size:-1},{name:rotation,type:float,size:4},{name:time,type:float,size:4},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/annotations/src/main/resources/revisions/MinerUnit/0.json b/annotations/src/main/resources/revisions/MinerUnit/0.json
deleted file mode 100644
index 5df97253d8..0000000000
--- a/annotations/src/main/resources/revisions/MinerUnit/0.json
+++ /dev/null
@@ -1 +0,0 @@
-{fields:[{name:ammo,type:int,size:4},{name:armor,type:float,size:4},{name:controller,type:mindustry.entities.units.UnitController,size:-1},{name:elevation,type:float,size:4},{name:health,type:float,size:4},{name:isShooting,type:boolean,size:1},{name:mineTile,type:mindustry.world.Tile,size:-1},{name:mounts,type:"mindustry.entities.units.WeaponMount[]",size:-1},{name:rotation,type:float,size:4},{name:shield,type:float,size:4},{name:spawnedByCore,type:boolean,size:1},{name:stack,type:mindustry.type.ItemStack,size:-1},{name:statuses,type:arc.struct.Seq<mindustry.entities.units.StatusEntry>,size:-1},{name:team,type:mindustry.game.Team,size:-1},{name:type,type:mindustry.type.UnitType,size:-1},{name:x,type:float,size:4},{name:y,type:float,size:4}]}
\ No newline at end of file
diff --git a/core/assets/bundles/bundle.properties b/core/assets/bundles/bundle.properties
index f692611442..45de1fb9cf 100644
--- a/core/assets/bundles/bundle.properties
+++ b/core/assets/bundles/bundle.properties
@@ -125,6 +125,7 @@ mod.reloadrequired = [scarlet]Restart Required
 mod.import = Import Mod
 mod.import.file = Import File
 mod.import.github = Import From GitHub
+mod.jarwarn = [scarlet]JAR mods are inherently unsafe.[]\nMake sure you're importing this mod from a trustworthy source!
 mod.item.remove = This item is part of the[accent] '{0}'[] mod. To remove it, uninstall that mod.
 mod.remove.confirm = This mod will be deleted.
 mod.author = [lightgray]Author:[] {0}
@@ -197,8 +198,8 @@ server.admins.none = No admins found!
 server.add = Add Server
 server.delete = Are you sure you want to delete this server?
 server.edit = Edit Server
-server.outdated = [crimson]Outdated Server![]
-server.outdated.client = [crimson]Outdated Client![]
+server.outdated = [scarlet]Outdated Server![]
+server.outdated.client = [scarlet]Outdated Client![]
 server.version = [gray]v{0} {1}
 server.custombuild = [accent]Custom Build
 confirmban = Are you sure you want to ban "{0}[white]"?
@@ -220,7 +221,7 @@ connecting.data = [accent]Loading world data...
 server.port = Port:
 server.addressinuse = Address already in use!
 server.invalidport = Invalid port number!
-server.error = [crimson]Error hosting server.
+server.error = [scarlet]Error hosting server.
 save.new = New Save
 save.overwrite = Are you sure you want to overwrite\nthis save slot?
 overwrite = Overwrite
@@ -230,8 +231,8 @@ save.delete.confirm = Are you sure you want to delete this save?
 save.delete = Delete
 save.export = Export Save
 save.import.invalid = [accent]This save is invalid!
-save.import.fail = [crimson]Failed to import save: [accent]{0}
-save.export.fail = [crimson]Failed to export save: [accent]{0}
+save.import.fail = [scarlet]Failed to import save: [accent]{0}
+save.export.fail = [scarlet]Failed to export save: [accent]{0}
 save.import = Import Save
 save.newslot = Save name:
 save.rename = Rename
@@ -486,7 +487,7 @@ zone.objective.attack = Destroy Enemy Core
 add = Add...
 boss.health = Boss Health
 
-connectfail = [crimson]Connection error:\n\n[accent]{0}
+connectfail = [scarlet]Connection error:\n\n[accent]{0}
 error.unreachable = Server unreachable.\nIs the address spelled correctly?
 error.invalidaddress = Invalid address.
 error.timedout = Timed out!\nMake sure the host has port forwarding set up, and that the address is correct!
@@ -545,7 +546,7 @@ unplaceable.sectorcaptured = [scarlet]Requires captured sector
 yes = Yes
 no = No
 info.title = Info
-error.title = [crimson]An error has occured
+error.title = [scarlet]An error has occured
 error.crashtitle = An error has occured
 unit.nobuild = [scarlet]Unit can't build
 blocks.input = Input
diff --git a/core/src/mindustry/core/Platform.java b/core/src/mindustry/core/Platform.java
index 767bfa993d..83390c82a8 100644
--- a/core/src/mindustry/core/Platform.java
+++ b/core/src/mindustry/core/Platform.java
@@ -136,7 +136,7 @@ public interface Platform{
      * @param extension File extension to filter
      */
     default void showFileChooser(boolean open, String extension, Cons<Fi> cons){
-        new FileChooser(open ? "$open" : "$save", file -> file.extension().toLowerCase().equals(extension), open, file -> {
+        new FileChooser(open ? "$open" : "$save", file -> file.extEquals(extension), open, file -> {
             if(!open){
                 cons.get(file.parent().child(file.nameWithoutExtension() + "." + extension));
             }else{
@@ -145,6 +145,19 @@ public interface Platform{
         }).show();
     }
 
+    /**
+     * Show a file chooser for multiple file types. Only supported on desktop.
+     * @param cons Selection listener
+     * @param extensions File extensions to filter
+     */
+    default void showMultiFileChooser(Cons<Fi> cons, String... extensions){
+        if(mobile){
+            showFileChooser(true, extensions[0], cons);
+        }else{
+            new FileChooser("$open", file -> Structs.contains(extensions, file.extension().toLowerCase()), true, cons).show();
+        }
+    }
+
     /** Hide the app. Android only. */
     default void hide(){
     }
diff --git a/core/src/mindustry/game/Universe.java b/core/src/mindustry/game/Universe.java
index b068b1337b..7712fbabe9 100644
--- a/core/src/mindustry/game/Universe.java
+++ b/core/src/mindustry/game/Universe.java
@@ -141,6 +141,8 @@ public class Universe{
         //TODO events
 
         Events.fire(new TurnEvent());
+
+        save();
     }
 
     public float secondsMod(float mod, float scale){
diff --git a/core/src/mindustry/io/SaveVersion.java b/core/src/mindustry/io/SaveVersion.java
index 9ee9081754..e03a22b2a5 100644
--- a/core/src/mindustry/io/SaveVersion.java
+++ b/core/src/mindustry/io/SaveVersion.java
@@ -74,7 +74,6 @@ public abstract class SaveVersion extends SaveFileReader{
         //prepare campaign data for writing
         if(state.isCampaign()){
             state.secinfo.prepare();
-            state.getSector().setLastSecond(universe.seconds());
         }
 
         //flush tech node progress
diff --git a/core/src/mindustry/mod/Mod.java b/core/src/mindustry/mod/Mod.java
index 5b4c31b7a0..eea38820c6 100644
--- a/core/src/mindustry/mod/Mod.java
+++ b/core/src/mindustry/mod/Mod.java
@@ -15,6 +15,11 @@ public class Mod{
 
     }
 
+    /** Called on clientside mods. Load content here. */
+    public void loadContent(){
+
+    }
+
     /** Register any commands to be used on the server side, e.g. from the console. */
     public void registerServerCommands(CommandHandler handler){
 
diff --git a/core/src/mindustry/mod/Mods.java b/core/src/mindustry/mod/Mods.java
index 7d00599884..e4758a20a3 100644
--- a/core/src/mindustry/mod/Mods.java
+++ b/core/src/mindustry/mod/Mods.java
@@ -460,6 +460,17 @@ public class Mods implements Loadable{
     /** Creates all the content found in mod files. */
     public void loadContent(){
 
+        //load class mod content first
+        for(LoadedMod mod : orderedMods()){
+            //hidden mods can't load content
+            if(mod.main != null && !mod.meta.hidden){
+                content.setCurrentMod(mod);
+                mod.main.loadContent();
+            }
+        }
+
+        content.setCurrentMod(null);
+
         class LoadRun implements Comparable<LoadRun>{
             final ContentType type;
             final Fi file;
@@ -583,7 +594,7 @@ public class Mods implements Loadable{
         Fi metaf = zip.child("mod.json").exists() ? zip.child("mod.json") : zip.child("mod.hjson").exists() ? zip.child("mod.hjson") : zip.child("plugin.json");
         if(!metaf.exists()){
             Log.warn("Mod @ doesn't have a 'mod.json'/'mod.hjson'/'plugin.json' file, skipping.", sourceFile);
-            throw new IllegalArgumentException("No mod.json found.");
+            throw new IllegalArgumentException("Invalid file: No mod.json found.");
         }
 
         ModMeta meta = json.fromJson(ModMeta.class, Jval.read(metaf.readString()).toString(Jformat.plain));
@@ -607,9 +618,9 @@ public class Mods implements Loadable{
 
         //make sure the main class exists before loading it; if it doesn't just don't put it there
         if(mainFile.exists()){
-            //other platforms don't have standard java class loaders
-            if(!headless && Version.build != -1){
-                throw new IllegalArgumentException("Java class mods are currently unsupported outside of custom builds.");
+            //mobile versions don't support class mods
+            if(mobile){
+                throw new IllegalArgumentException("Java class mods are not supported on mobile.");
             }
 
             URLClassLoader classLoader = new URLClassLoader(new URL[]{sourceFile.file().toURI().toURL()}, ClassLoader.getSystemClassLoader());
diff --git a/core/src/mindustry/type/Sector.java b/core/src/mindustry/type/Sector.java
index 0a5004b2f5..5d922979a6 100644
--- a/core/src/mindustry/type/Sector.java
+++ b/core/src/mindustry/type/Sector.java
@@ -6,7 +6,6 @@ import arc.struct.*;
 import arc.util.ArcAnnotate.*;
 import arc.util.*;
 import arc.util.io.*;
-import arc.util.noise.*;
 import mindustry.*;
 import mindustry.ctype.*;
 import mindustry.game.Saves.*;
@@ -29,7 +28,7 @@ public class Sector{
     public @Nullable SectorPreset preset;
 
     /** Sector enemy hostility from 0 to 1 */
-    public float hostility;
+    //public float hostility;
 
     //TODO implement a dynamic launch period
     public int launchPeriod = 10;
@@ -57,7 +56,7 @@ public class Sector{
 
     /** @return whether the enemy has a generated base here. */
     public boolean hasEnemyBase(){
-        return hostility >= 0.02f && (save == null || save.meta.rules.waves);
+        return is(SectorAttribute.base) && (save == null || save.meta.rules.waves);
     }
 
     public boolean isBeingPlayed(){
@@ -80,7 +79,7 @@ public class Sector{
 
     public void generate(){
         //TODO use simplex and a seed
-        hostility = Math.max(Noise.snoise3(tile.v.x, tile.v.y, tile.v.z, 0.5f, 0.4f), 0);
+        //hostility = Math.max(Noise.snoise3(tile.v.x, tile.v.y, tile.v.z, 0.5f, 0.4f), 0);
     }
 
     public boolean locked(){
@@ -156,7 +155,8 @@ public class Sector{
         return (seconds / 60) + ":" + (sf < 10 ? "0" : "") + sf;
     }
 
-    /** @return the stored amount of time spent in this sector this turn in ticks. */
+    /** @return the stored amount of time spent in this sector this turn in ticks.
+     * Do not use unless you know what you're doing. */
     public float getStoredTimeSpent(){
         return Core.settings.getFloat(key("time-spent"));
     }
@@ -165,6 +165,8 @@ public class Sector{
         put("seconds-passed", number);
     }
 
+    /** @return how much time has passed in this sector without the player resuming here.
+     * Used for resource production calculations. */
     public long getSecondsPassed(){
         return Core.settings.getLong(key("seconds-passed"));
     }
@@ -284,6 +286,8 @@ public class Sector{
         /** Has snow. */
         snowy,
         /** Has sandstorms. */
-        desert
+        desert,
+        /** Has an enemy base. */
+        base
     }
 }
diff --git a/core/src/mindustry/ui/dialogs/ModsDialog.java b/core/src/mindustry/ui/dialogs/ModsDialog.java
index 0132f954e7..ddb72815b4 100644
--- a/core/src/mindustry/ui/dialogs/ModsDialog.java
+++ b/core/src/mindustry/ui/dialogs/ModsDialog.java
@@ -77,15 +77,24 @@ public class ModsDialog extends BaseDialog{
                     t.button("$mod.import.file", Icon.file, bstyle, () -> {
                         dialog.hide();
 
-                        platform.showFileChooser(true, "zip", file -> {
-                            try{
-                                mods.importMod(file);
-                                setup();
-                            }catch(IOException e){
-                                ui.showException(e);
-                                e.printStackTrace();
+                        platform.showMultiFileChooser(file -> {
+                            Runnable go = () -> {
+                                try{
+                                    mods.importMod(file);
+                                    setup();
+                                }catch(IOException e){
+                                    ui.showException(e);
+                                    e.printStackTrace();
+                                }
+                            };
+
+                            //show unsafe jar file warning
+                            if(file.extEquals("jar")){
+                                ui.showConfirm("$warning", "$mod.jarwarn", go);
+                            }else{
+                                go.run();
                             }
-                        });
+                        }, "zip", "jar");
                     }).margin(12f);
 
                     t.row();
diff --git a/gradle.properties b/gradle.properties
index 34f08723e2..78b0b3e1c8 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,3 +1,3 @@
 org.gradle.daemon=true
 org.gradle.jvmargs=-Xms256m -Xmx1024m
-archash=6ed1b560047eaaf9ae83176526de51e5a49cadc3
+archash=b877b22de07db3cd2843a59eb92f5dfe1c61ae78