Add emitter sound effect.

game.scm

@@ -66,6 +66,7 @@
 (define audio:no (load-sound-effect "no"))
 (define audio:exit (load-sound-effect "exit"))
 (define audio:pickup (load-sound-effect "pickup"))
+(define audio:emit (load-sound-effect "emit"))
 (define audio:die (load-sound-effect "die"))
 (define audio:gate (load-sound-effect "gate"))
 (define audio:warp (load-sound-effect "warp"))
@@ -229,6 +230,8 @@
                  ;; TODO: Maybe show a little achievement popup when all gems
                  ;; are collected?
                  (set! *gems* (cons *level-idx* *gems*)))
+                (('emit x y)
+                 (play-sound-effect audio:emit))
                 ((or ('gate-open x y) ('gate-close x y))
                  (play-sound-effect audio:gate))
                 ((or ('floor-switch-on x y) ('floor-switch-off x y))

modules/game/actors.scm

@@ -134,6 +134,7 @@
      (let ((t ($ timer)))
        (cond
         ((= (modulo t interval) 0)
+         ($ grid-info 'append-event `(emit ,x ,y))
          'electron-head)
         ((= (modulo t interval) 1)
          'electron-tail)