I'm making a top-down space shooter, plays like Asteroids, but with a great variety of levels, enemies bosses, a few different weapons, etc... the enemies are all aliens set to invade Earth, and you basically level by level move from our Solar system to wherever the aliens live(I know, totally original right). I'm looking for some possible ideas for Easter Egg type things you can find. I don't know how many I will have, and I'm not decided if I will even have one per level. These things should in theory be somewhat hard to find(though likely easy if you already know where they are), so an example would be hidden in an area you can't get to behind indestructible walls, except a small section of the wall is actually destructible.... In fact, I'm open to ideas of things that could also be places to find these things besides just behind walls. The first idea I had was that you find a cow, in outer space, or on a planet somewhere. It speaks and tells you how it was abducted by the aliens and then used for experiments, leaving it mutated. Its a pretty farfetched idea but theoretically makes a certain sense. To sum it up, I'm looking for similar ideas, and possible ideas of where in levels you can find these things besides just finding walls that you can destroy. Thanks in advance for any thoughts!