+ special case
	no collision with all-white frames (allow walking through bridges)
	no climbing on spikes
+ have bridge stop building when hits wall
	(real game, reverses too maybe?)



+ bridges you can walk through from underneath, not
	sure how to implement that
+ bashes stop when nothing to right/left

+ wait a second after last lemming gone to exit
+ dig off the map, end level
+ fill in some of the ground so we don't get stuck when digging
+ See if the jerky animation is due to starting at an odd x vs
	even x, maybe we should start animation 4 frames in if that's
	the case.  Or maybe it's the shift for odd frames, make
	the shift the other way if walking left/right
+ Add climber
+ Add builder
+ Make particles thicker?  Look fine, not show up in recordings
+ Erase particles as last step

+ when nuke, they should stop coming out of the door
+ offset the frames when nuking so not simultaneous
+ on explosion, start with invisible 6 so we always get a full 5s

+ nuke/exploding should not happen if lemming is splatting
	or already exploding
+ green flame for ice level?