Games like Super Mutant Alien Assault
Games like Super Mutant Alien Assault include Broforce, Skul: The Hero Slayer, Vampire Survivors, Risk of Rain (2013), and The Binding of Isaac: Rebirth. We matched them by the tags players give Super Mutant Alien Assault on Steam (Action, Action Roguelike, Indie, Pixel Graphics, and Platformer): closest matches first, and among equally close ones the better-known games.

Broforce
Shared: Action · Pixel Graphics · Platformer

Skul: The Hero Slayer
Shared: Action · Indie · Action Roguelike

Vampire Survivors
Shared: Action Roguelike · Pixel Graphics · Indie

Risk of Rain (2013)
Shared: Action Roguelike · Indie · Action

The Binding of Isaac: Rebirth
Shared: Action Roguelike · Indie · Pixel Graphics

Enter the Gungeon
Shared: Action Roguelike · Pixel Graphics · Indie

Spelunky
Shared: Action Roguelike · Platformer · Indie

Rogue Legacy
Shared: Indie · Action Roguelike · Action

Nuclear Throne
Shared: Action Roguelike · Indie · Pixel Graphics

BlazBlue Entropy Effect
Shared: Action Roguelike · Action · 2D

Downwell
Shared: Action Roguelike · Pixel Graphics · Indie

Dungreed
Shared: Action Roguelike · Pixel Graphics · Action

Shovel Knight: Treasure Trove
Shared: Pixel Graphics · Platformer · Indie

Duck Game
Shared: Action · Pixel Graphics · Indie

Katana ZERO
Shared: Action · Pixel Graphics · Platformer

Wizard of Legend
Shared: Action Roguelike · Pixel Graphics · Action

Cuphead
Shared: Platformer · Local Co-Op · Indie

Dead Cells
Shared: Action Roguelike · Pixel Graphics · 2D

Huntdown
Shared: Action · Pixel Graphics · Local Co-Op

UFO 50
Shared: Indie · Action · Pixel Graphics

Noita
Shared: Pixel Graphics · Indie · Action Roguelike

Megabonk
Shared: Action Roguelike · Indie · Action

SANABI
Shared: Action · Pixel Graphics · Indie

Celeste
Shared: Pixel Graphics · Indie · Platformer