Silly idea for the main menu. :P

[Apjjm]

Pictures
The thunder occurs every 50 seconds (approx). The monster will only appear on every second thunder & lightning. Using the approach I did you could change that to whatever though (note the thunder sound is controlled by a box light under the grunt as it was the only way I could think of to hack in a delay but keep it in sync (at least within a 30 minute time-frame)).
Probably could have picked a better gobo, but well, that is trivial to change - this was just to see if I could do the effect without any new files other than the map.