The source code of VVVVVV is now public! https://github.com/TerryCavanagh/vvvvvv
Did you check the IS help thread? If not, make sure to to that in the future.Anyway, here's the entity list for createentity(): http://distractionware.com/forum/index.php?topic=1089.msg13668;topicseen#msg13668Keep in mind that you can only make purple boxes unless you're in a particular room, where it'll turn into another enemy.
Keep in mind that you can only make purple boxes unless you're in a particular room