Games like CPU Invaders - 3i Atlas
Games like CPU Invaders - 3i Atlas include Party Animals, Stick Fight: The Game, Team Fortress 2, Gang Beasts, and Garry's Mod. We matched them by the tags players give CPU Invaders - 3i Atlas on Steam (Funny, Casual, 2.5D, Action, and Hero Shooter): closest matches first, and among equally close ones the better-known games.

Party Animals
Shared: Funny · Casual · Cute

Stick Fight: The Game
Shared: Funny · Action · Casual

Team Fortress 2
Shared: Hero Shooter · Funny · Action

Gang Beasts
Shared: Funny · Action · Casual

Garry's Mod
Shared: Funny · Casual · Physics

Goat Simulator
Shared: Funny · Casual · Action

MARVEL Tōkon: Fighting Souls
Shared: Casual · Action · 2.5D

Airscape - The Fall of Gravity
Shared: Casual · Shoot 'Em Up · 2.5D

Plants vs. Zombies: Battle for Neighborville™
Shared: Funny · Hero Shooter · Casual

Donut County
Shared: Casual · Funny · Cute

Planes, Bullets and Vodka
Shared: Casual · Action · Shoot 'Em Up

Bit Blaster XL
Shared: Casual · Shoot 'Em Up · Action

Placid Plastic Duck Simulator
Shared: Casual · Cute · Funny

Iron Snout
Shared: Funny · Action · 2D Fighter

Human Fall Flat
Shared: Funny · Action · Physics

Shower With Your Dad Simulator 2015: Do You Still Shower With Your Dad
Shared: Funny · Casual · Action

Turnip Boy Commits Tax Evasion
Shared: Funny · Cute · Action

Pikuniku
Shared: Casual · Funny · Cute

DJMAX RESPECT V
Shared: Casual · Action · Cute

CPU Invaders - Micro Spheres
Shared: Casual · Funny · Action

Katamari Damacy REROLL
Shared: Casual · Funny · Action

DNF Duel
Shared: Action · 2.5D · Casual

Shooty Skies
Shared: Funny · Action · Shoot 'Em Up

Puyo Puyo™ Tetris® 2
Shared: Casual · Action · Cute