diff --git a/modules/game/actors.scm b/modules/game/actors.scm
index feedfdf..9798e04 100644
--- a/modules/game/actors.scm
+++ b/modules/game/actors.scm
@@ -44,13 +44,6 @@
     ('electron-head 'electron-tail)
     ('electron-tail 'copper)))
 
-(define (grid-electrified? neighbor-grid)
-  (let lp ((i 0))
-    (cond
-     ((= i (vector-length neighbor-grid)) #f)
-     ((eq? (vector-ref neighbor-grid i) 'electron-head) #t)
-     (else (lp (+ i 1))))))
-
 (define (electron-head-count neighbor-grid)
   (define (check state)
     (match state
@@ -372,47 +365,48 @@
   (define alive? (spawn ^cell #t))
   (define countdown (spawn ^cell -1))
   (define pushed? (spawn ^cell))
-  (define* (light-fuse #:optional (time 2))
-    ($ countdown time))
+  (define (light-fuse)
+    ($ countdown 2))
   (match-lambda*
     (('type) 'bomb)
     (('position) ($ position))
     (('tick grid-info)
      ($ pushed? #f)
      (when (> ($ countdown) 0)
-       ($ countdown (- ($ countdown) 1)))
-     (when (= ($ countdown) 0)
-       ($ alive? #f)
-       (match ($ position)
-         (#(x y z)
-          (do ((ix (- x 1) (+ ix 1)))
-              ((> ix (+ x 1)))
-            (do ((iy (- y 1) (+ iy 1)))
-                ((> iy (+ y 1)))
-              (unless (and (= ix x) (= iy y))
-                (let ((obj (match ($ grid-info 'occupants ix iy)
-                             (() #f)
-                             ((obj . rest) obj))))
-                  (when obj
-                    (match ($ obj 'type)
-                      ((or 'bomb 'brick)
-                       ($ obj 'explode))
-                      ('player
-                       ($ obj 'explode)
-                       ($ grid-info 'append-event `(player-death ,ix ,iy)))
-                      (_ #f)))))))
-          ($ grid-info 'append-event `(explosion ,x ,y))))))
+       (let ((cd (1- ($ countdown))))
+         ($ countdown cd)
+         (when (= cd 0)
+           ($ alive? #f)
+           (match ($ position)
+             (#(x y z)
+              (do ((ix (- x 1) (+ ix 1)))
+                  ((> ix (+ x 1)))
+                (do ((iy (- y 1) (+ iy 1)))
+                    ((> iy (+ y 1)))
+                  (unless (and (= ix x) (= iy y))
+                    (let ((obj (match ($ grid-info 'occupants ix iy)
+                                 (() #f)
+                                 ((obj . rest) obj))))
+                      (when obj
+                        (match ($ obj 'type)
+                          ((or 'bomb 'brick)
+                           ($ obj 'explode))
+                          ('player
+                           ($ obj 'explode)
+                           ($ grid-info 'append-event `(player-death ,ix ,iy)))
+                          (_ #f)))))))
+              ($ grid-info 'append-event `(explosion ,x ,y))))))))
     (('post-tick grid-info) #f)
     (('enter obj grid-info) #f)
     (('exit obj grid-info) #f)
     (('wire-state grid-info from from-x from-y) #f)
     (('update-wire-state grid-info neighbor-grid)
      (when (and (< ($ countdown) 0)
-                (grid-electrified? neighbor-grid))
+                (> (electron-head-count neighbor-grid) 0))
        (light-fuse)))
     (('alive?) ($ alive?))
     (('describe) `(bomb ,($ position) ,($ countdown)))
-    (('explode) (light-fuse 1))
+    (('explode) (light-fuse))
     (('activate grid-info) #f)
     (('deactivate grid-info) #f)
     (('collide other offset grid-info)
@@ -437,7 +431,7 @@
 
 ;; A gem that has already been collected previously will still appear
 ;; in the level but it will be drawn differently.
-(define (^gem bcom x y previously-collected?)
+(define* (^gem bcom x y previously-collected? #:optional test?)
   (define position (vector x y 1))
   (define picked-up? (spawn ^cell))
   (match-lambda*
diff --git a/modules/game/level.scm b/modules/game/level.scm
index 5463938..08a6b95 100644
--- a/modules/game/level.scm
+++ b/modules/game/level.scm
@@ -67,7 +67,12 @@
           (when (< x width)
             (let* ((i (+ (* y width) x))
                    (pos (vec2 (* x tile-width) (* y tile-height)))
-                   (id (bytevector-u16-native-ref background (* i 2)))
+                   (id (case (bytevector-u16-native-ref background (* i 2))
+                         ((120) 81)
+                         ((121) 82)
+                         ((122) 85)
+                         ((123) 105)
+                         (else => (lambda (v) v))))
                    (tile (make-level-tile pos id)))
               (vector-set! background* i tile))
             (x-loop (1+ x))))