Mega Fatty is a large, bloated humanoid with beady eyes streaming bloody tears. He has one tooth at the bottom of his blood-stained mouth. Furthermore, he has stubby arms.
Mega Fatty will not move or chase the player, unless jumping up and landing in the place where Issac is. (similar to Monstro's cycle of attack) The player must be wary, as his 'pooping' attacks are long range and also tracking. He is usually easy to kill after one or more encounters with him.
Mega Fatty has a number of different attacks:
- Mega Fatty can hold, and fart, pooping out a Squirt . He may poop out more than one.
- Mega Fatty can hold, and fart, also pooping out an array of "poop" bullets towards Isaac.
- Mega Fatty jumps up, then lands in the position Issac is, leaving red creep around where he landed.
- Mega Fatty opens his mouth, and then poops out an array of homing brown bullets towards Issac. The bullets will keep on shooting at Isaac for a while, then will stop.
In the The Binding of Isaac: Afterbirth expansion, Mega Fatty has two different champion variants.
- He may be based (or similar to) the boss Gluttony, one of the seven deadly sins.
- Oddly enough, during his death animation, Mega Fatty's face look eerily similar to Gluttony.