In all seriousness, why do you use pointers, 64 bit indices, or even worse, GUIDs in your game runtime?
I assume sloppy/lazy programming.
99% of the time, a 16 bit ID is more then enough.
For an entity ID in a very generic engine, 32 bit is more then enough too.
fun fact: models in the source engine can each have up to 2.147 billion mouths and up to 4,611,686,000,000,000,000 eyeballs (up to 2.147 billion eyeballs per body part)