diff --git a/scripts/debug.js b/scripts/debug.js
index d5e1709..283080e 100644
--- a/scripts/debug.js
+++ b/scripts/debug.js
@@ -241,6 +241,7 @@ var Time = {
   },
 
   pause() {
+    Time.stash = Time.timescale;
     Time.timescale = 0;
   },
 
diff --git a/scripts/entity.js b/scripts/entity.js
index 573e1dc..d0efdbe 100644
--- a/scripts/entity.js
+++ b/scripts/entity.js
@@ -123,6 +123,10 @@ var gameobject = {
 
       set phys(x) { set_body(1, this.body, x); },
       get phys() { return q_body(0,this.body); },
+//      set mask(x) { cmd(41, this.body, x); },
+//      get mask() { return cmd(43, this.body); },
+//      set category(x) { cmd(40, this.body, x); },
+//      get category() { return cmd(42, this.body); },
       get velocity() { return q_body(3, this.body); },
       set velocity(x) { set_body(9, this.body, x); },
       get angularvelocity() { return Math.rad2deg(q_body(4, this.body)); },
@@ -237,7 +241,7 @@ var gameobject = {
       world2this(pos) { return cmd(70, this.body, pos); },
       this2world(pos) { return cmd(71, this.body,pos); },
       set layer(x) { cmd(75,this.body,x); },
-      get layer() { return 0; },
+      get layer() { cmd(77,this.body); },
       alive() { return this.body >= 0; },
       in_air() { return q_body(7, this.body);},
       on_ground() { return !this.in_air(); },
@@ -336,7 +340,6 @@ var gameobject = {
        this.objects.forEach(function(x) { x.sync(); });
       },
 
-
       /* Bounding box of the object in world dimensions */
       boundingbox() {
 	var boxes = [];
diff --git a/scripts/input.js b/scripts/input.js
index 7ad78c0..1cb2aca 100644
--- a/scripts/input.js
+++ b/scripts/input.js
@@ -135,7 +135,7 @@ var Player = {
       }
 
       if (!pawn.inputs?.[cmd]) {
-        if (pawn.inputs.block) return;
+        if (pawn.inputs?.block) return;
 	continue;
       }
 
diff --git a/scripts/physics.js b/scripts/physics.js
index 0bb1163..a43f65a 100644
--- a/scripts/physics.js
+++ b/scripts/physics.js
@@ -52,32 +52,16 @@ physics.doc.box_point_query = "Returns the subset of points from a given list th
 
 var Collision = {
   types: {},
-  num: 10,
+  num: 32,
   set_collide(a, b, x) {
     this.types[a][b] = x;
     this.types[b][a] = x;
+    this.sync();
   },
   sync() {
     for (var i = 0; i < this.num; i++)
       cmd(76,i,this.types[i]);
   },
-  types_nuke() {
-    Nuke.newline(this.num+1);
-    Nuke.label("");
-    for (var i = 0; i < this.num; i++) Nuke.label(i);
-    
-    for (var i = 0; i < this.num; i++) {
-      Nuke.label(i);
-      for (var j = 0; j < this.num; j++) {
-        if (j < i)
-	  Nuke.label("");
-	else {
-          this.types[i][j] = Nuke.checkbox(this.types[i][j]);
-  	  this.types[j][i] = this.types[i][j];
-	}
-      }
-    }
-  },
 };
 
 for (var i = 0; i < Collision.num; i++) {
@@ -86,3 +70,5 @@ for (var i = 0; i < Collision.num; i++) {
     Collision.types[i][j] = false;
 };
 
+Collision.sync();
+
diff --git a/source/engine/gameobject.c b/source/engine/gameobject.c
index 6b813c4..affe6f6 100644
--- a/source/engine/gameobject.c
+++ b/source/engine/gameobject.c
@@ -50,6 +50,11 @@ int shape2gameobject(cpShape *shape) {
   return s->go;
 }
 
+struct gameobject *shape2go(cpShape *shape)
+{
+  return id2go(shape2gameobject(shape));
+}
+
 int pos2gameobject(cpVect pos) {
   cpShape *hit = phys2d_query_pos(pos);
 
@@ -84,6 +89,16 @@ int go2id(struct gameobject *go) {
   return id_from_gameobject(go);
 }
 
+uint32_t go2category(struct gameobject *go)
+{
+  return 0;
+}
+
+uint32_t go2mask(struct gameobject *go)
+{
+  return 0;
+}
+
 void go_shape_apply(cpBody *body, cpShape *shape, struct gameobject *go) {
   cpShapeSetFriction(shape, go->f);
   cpShapeSetElasticity(shape, go->e);
@@ -91,8 +106,8 @@ void go_shape_apply(cpBody *body, cpShape *shape, struct gameobject *go) {
 
   cpShapeFilter filter;
   filter.group = go2id(go);
-  filter.categories = CP_ALL_CATEGORIES;//1<<go->layer;
-  filter.mask = CP_ALL_CATEGORIES;//category_masks[go->layer];
+  filter.categories = 1<<go->layer;
+  filter.mask = category_masks[go->layer];
   cpShapeSetFilter(shape, filter);
 
   struct phys2d_shape *ape = cpShapeGetUserData(shape);
diff --git a/source/engine/gameobject.h b/source/engine/gameobject.h
index 40c24f6..b2a5982 100644
--- a/source/engine/gameobject.h
+++ b/source/engine/gameobject.h
@@ -53,6 +53,9 @@ int go2id(struct gameobject *go);
 int body2id(cpBody *body);
 cpBody *id2body(int id);
 int shape2gameobject(cpShape *shape);
+struct gameobject *shape2go(cpShape *shape);
+uint32_t go2category(struct gameobject *go);
+uint32_t go2mask(struct gameobject *go);
 
 void go_shape_apply(cpBody *body, cpShape *shape, struct gameobject *go);
 
diff --git a/source/engine/jsffi.c b/source/engine/jsffi.c
index 74a23d1..259321d 100644
--- a/source/engine/jsffi.c
+++ b/source/engine/jsffi.c
@@ -50,13 +50,11 @@ static JSClassDef js_ptr_class = { "POINTER" };
 void js_setprop_str(JSValue obj, const char *prop, JSValue v)
 {
   JS_SetPropertyStr(js, obj, prop, v);
-//  JS_FreeValue(js,v);
 }
 
 void js_setprop_num(JSValue obj, uint32_t i, JSValue v)
 {
   JS_SetPropertyUint32(js, obj, i, v);
-//  JS_FreeValue(js,v);
 }
 
 JSValue js_getpropstr(JSValue v, const char *str)
@@ -826,6 +824,7 @@ JSValue duk_cmd(JSContext *js, JSValueConst this, int argc, JSValueConst *argv)
     break;
 
   case 77:
+    ret = int2js(js2go(argv[1])->layer);
     break;
 
   case 78: