diff --git a/js/main.js b/js/main.js
index 7806c04..9f1071d 100644
--- a/js/main.js
+++ b/js/main.js
@@ -234,6 +234,8 @@ class Level {
         this.tic_counter = 0;
 
         this.hint_shown = null;
+        // TODO in lynx/steam, this carries over between levels; in tile world, you can set it manually
+        this.force_floor_direction = 'north';
 
         let n = 0;
         let connectables = [];
@@ -615,12 +617,25 @@ class Level {
         }
     }
 
+    // -------------------------------------------------------------------------
+    // Level alteration methods.  EVERYTHING that changes the state of a level,
+    // including the state of a single tile, should do it through one of these
+    // for undo/rewind purposes
+
     collect_chip() {
         if (this.chips_remaining > 0) {
             this.chips_remaining--;
         }
     }
 
+    // Get the next direction a random force floor will use.  They share global
+    // state and cycle clockwise.
+    get_force_floor_direction() {
+        let d = this.force_floor_direction;
+        this.force_floor_direction = DIRECTIONS[d].right;
+        return d;
+    }
+
     // TODO make a set of primitives for actually altering the level that also
     // record how to undo themselves
     make_slide(actor, mode) {
diff --git a/js/tiletypes.js b/js/tiletypes.js
index 53e36f5..4a3aeba 100644
--- a/js/tiletypes.js
+++ b/js/tiletypes.js
@@ -225,7 +225,11 @@ const TILE_TYPES = {
         },
     },
     force_floor_all: {
-        // TODO cc2 cycles these...
+        // TODO ms: this is random, and an acting wall to monsters (!)
+        on_arrive(me, level, other) {
+            other.direction = level.get_force_floor_direction();
+            level.make_slide(other, 'force');
+        },
     },
     bomb: {
         // TODO explode