Starcraft does this for it's map animations. Each player in the game has a different color (so you can tell who's units are who's) and on some level that color is implemented as an index into memory, so if you set the player color above what the designers intended you can end up with wonky colors and (if memory serves correctly) some indices can land you in the rotating palette and give you subtile animated colors on your units. Most where just garbage memory though. This leads to a crash too because unlike most units the special 'flag' unit (for capture the flag) has a different portrait for each player color. It's also indexed by player color, so if you click on a flag of an invalid-color player, it crashes the game. This lead to fun maps like 'dont click the flag' but also woe in long running maps where players could click crash flags by mistake. Again, if memory serves, the crash was fixed by some hacks people would use in Roleplay maps (vision hacking allowed you to stack buildings) so RP map makers would include then anyway. Units to use as labels where at a premium in RP maps, you see...