List of other games that Isaac appears in

[Steven]

The Basement Collection

http://store.steampowered.com/app/214790/The_Basement_Collection/
(appears in aether)

Creepy Castle

http://store.steampowered.com/app/450440/Creepy_Castle/
(appears as eden and eve)

SOYF: S#!T ON YOUR FRIENDS

http://store.steampowered.com/app/648880/SOYF_ST_ON_YOUR_FRIENDS/
(appears as a guest character)

The End Is Nigh

http://store.steampowered.com/app/583470/The_End_Is_Nigh/
(appears as a cameo)

Rock of Ages 2: Bigger & Boulder™

http://store.steampowered.com/app/434460/Rock_of_Ages_2_Bigger__Boulder/
(appears as limited dlc)

[Marianne]

The list has become longer in the mean time!

More games where Isaac appears in are:
- Blade Strangers (a 2D Fighting game where Isaac appears as a fighter, together with some other fighting characters from other games: Umihara Kawasa, Shovel Knight, etc.).
- Coloring Game Little City (where he appears as a picture to color in).
- Crystal Crisis (where he also appears as a fighting character, together with another guest character: Astro Boy).
- Save me Mr Tako: Tasukete Tako-San (where he appears in a personal bonus level to himself, and Shovel Knight appears in here too).

I wonder if there are any more i have missed.

[Steven]

Wow, i didn't realize that.