Contents may include:
A pond full of fish,
A hungry, hungry black hole,
Upgradeable spawners to keep the pond topped up,
And an infinite supply of fish!
Try to catch fish the old fashioned way. That doesn't work, so use a black-hole fueled whirlpool instead.
Upgrade your fish to make a bigger and bigger whirlpool
Drain the pond - only to discover another pond below the pond!
Cross-breed fish to create the ultimate scoring machine
Reach the center of the Earth - and destroy all life in a very fishy way.
I apologize for the fish pun earlier in the description. This is the only one, I promise