diff --git a/core/assets/maps/four.msav b/core/assets/maps/four.msav
new file mode 100644
index 0000000000..e33f7e2c33
Binary files /dev/null and b/core/assets/maps/four.msav differ
diff --git a/core/src/mindustry/content/ErekirTechTree.java b/core/src/mindustry/content/ErekirTechTree.java
index 36980357ae..7de78f2c9a 100644
--- a/core/src/mindustry/content/ErekirTechTree.java
+++ b/core/src/mindustry/content/ErekirTechTree.java
@@ -19,7 +19,7 @@ public class ErekirTechTree{
         costMultipliers.put(Items.surgeAlloy, 4);
         costMultipliers.put(Items.phaseFabric, 4);
         costMultipliers.put(Items.thorium, 9);
-        costMultipliers.put(Items.graphite, 10);
+        costMultipliers.put(Items.graphite, 9);
 
         //TODO gate behind capture
 
@@ -54,7 +54,9 @@ public class ErekirTechTree{
                 });
 
                 //TODO should only be unlocked in unit sector
-                node(constructor, Seq.with(new Research(siliconArcFurnace), erekirSector.first()), () -> {
+                node(constructor, Seq.with(new Research(siliconArcFurnace), new OnSector(four)), () -> {
+
+                    //TODO further limitations
                     node(payloadLoader, () -> {
                         node(payloadUnloader, () -> {
                             node(payloadPropulsionTower, () -> {
@@ -78,7 +80,7 @@ public class ErekirTechTree{
             //TODO move into turbine condenser?
             node(plasmaBore, () -> {
                 node(impactDrill, Seq.with(new OnSector(aware)), () -> {
-                    node(largePlasmaBore, () -> {
+                    node(largePlasmaBore, Seq.with(new OnSector(four)), () -> {
                         node(eruptionDrill, () -> {
 
                         });
@@ -96,14 +98,14 @@ public class ErekirTechTree{
                         });
                     });
 
-                    node(beamTower, () -> {
+                    node(beamTower, Seq.with(new OnSector(four)), () -> {
 
                     });
 
 
                     node(regenProjector, () -> {
                         //TODO more tiers of build tower or "support" structures like overdrive projectors
-                        node(buildTower, () -> {
+                        node(buildTower, Seq.with(new OnSector(four)), () -> {
 
                         });
                     });
@@ -134,7 +136,7 @@ public class ErekirTechTree{
                     node(cliffCrusher, () -> {
                         node(electrolyzer, Seq.with(new OnSector(three)), () -> {
                             node(oxidationChamber, () -> {
-                                node(electricHeater, () -> {
+                                node(electricHeater, Seq.with(new OnSector(four)), () -> {
                                     node(heatRedirector, () -> {
 
                                     });
@@ -157,7 +159,7 @@ public class ErekirTechTree{
                                 });
                             });
 
-                            node(slagIncinerator, () -> {
+                            node(slagIncinerator, Seq.with(new OnSector(four)), () -> {
 
                                 node(slagCentrifuge, () -> {
 
@@ -194,7 +196,7 @@ public class ErekirTechTree{
                 });
             });
 
-            node(coreCitadel, () -> {
+            node(coreCitadel, Seq.with(new SectorComplete(four)), () -> {
                 node(coreAcropolis, () -> {
 
                 });
@@ -204,7 +206,9 @@ public class ErekirTechTree{
             node(onset, () -> {
                 node(aware, Seq.with(new SectorComplete(onset), new Research(ductRouter)), () -> {
                     node(three, Seq.with(new SectorComplete(aware), new Research(reinforcedContainer), new Research(ductUnloader), new Research(ventCondenser)), () -> {
+                        node(four, Seq.with(new SectorComplete(three), new Research(electrolyzer), new Research(oxidationChamber), new Research(chemicalCombustionChamber)), () -> {
 
+                        });
                     });
                 });
             });
diff --git a/core/src/mindustry/content/Fx.java b/core/src/mindustry/content/Fx.java
index eb82e01bf8..44f6514f44 100644
--- a/core/src/mindustry/content/Fx.java
+++ b/core/src/mindustry/content/Fx.java
@@ -1046,7 +1046,7 @@ public class Fx{
     }),
 
     ventSteam = new Effect(140f, e -> {
-        color(Pal.vent, e.fslope() * 0.85f);
+        color(e.color, e.fslope() * 0.85f);
 
         float length = 3f + e.finpow() * 10f;
         rand.setSeed(e.id);
diff --git a/core/src/mindustry/content/SectorPresets.java b/core/src/mindustry/content/SectorPresets.java
index 359af7de91..d0483036ad 100644
--- a/core/src/mindustry/content/SectorPresets.java
+++ b/core/src/mindustry/content/SectorPresets.java
@@ -12,7 +12,7 @@ public class SectorPresets{
     impact0078, desolateRift, nuclearComplex, planetaryTerminal,
     coastline, navalFortress,
 
-    onset, aware, three
+    onset, aware, three, four
     ;
 
     public static void load(){
@@ -128,6 +128,10 @@ public class SectorPresets{
             difficulty = 5;
         }};
 
+        four = new SectorPreset("four", erekir, 29){{
+            difficulty = 6;
+        }};
+
         //endregion
     }
 }
diff --git a/core/src/mindustry/entities/comp/FireComp.java b/core/src/mindustry/entities/comp/FireComp.java
index 4ff123d1bb..33f6e3c4ae 100644
--- a/core/src/mindustry/entities/comp/FireComp.java
+++ b/core/src/mindustry/entities/comp/FireComp.java
@@ -28,7 +28,6 @@ abstract class FireComp implements Timedc, Posc, Syncc, Drawc{
     public static final TextureRegion[] regions = new TextureRegion[frames];
 
     @Import float time, lifetime, x, y;
-    @Import int id;
 
     Tile tile;
     private transient Block block;
diff --git a/core/src/mindustry/world/blocks/environment/SteamVent.java b/core/src/mindustry/world/blocks/environment/SteamVent.java
index 9daf441842..6ab3eccc75 100644
--- a/core/src/mindustry/world/blocks/environment/SteamVent.java
+++ b/core/src/mindustry/world/blocks/environment/SteamVent.java
@@ -1,5 +1,6 @@
 package mindustry.world.blocks.environment;
 
+import arc.graphics.*;
 import arc.graphics.g2d.*;
 import arc.math.*;
 import arc.math.geom.*;
@@ -7,6 +8,7 @@ import arc.util.*;
 import mindustry.*;
 import mindustry.content.*;
 import mindustry.entities.*;
+import mindustry.graphics.*;
 import mindustry.world.*;
 
 import static mindustry.Vars.*;
@@ -27,6 +29,7 @@ public class SteamVent extends Floor{
 
     public Block parent = Blocks.air;
     public Effect effect = Fx.ventSteam;
+    public Color effectColor = Pal.vent;
     public float effectSpacing = 15f;
 
     static{
@@ -58,7 +61,7 @@ public class SteamVent extends Floor{
     @Override
     public void renderUpdate(UpdateRenderState state){
         if(state.tile.block() == Blocks.air && (state.data += Time.delta) >= effectSpacing){
-            effect.at(state.tile.x * tilesize - tilesize, state.tile.y * tilesize - tilesize);
+            effect.at(state.tile.x * tilesize - tilesize, state.tile.y * tilesize - tilesize, effectColor);
             state.data = 0f;
         }
     }