Games like Slam Fighter II
Games like Slam Fighter II include Muse Dash, Stick Fight: The Game, Undertale, Rivals of Aether, and Rhythm Doctor. We matched them by the tags players give Slam Fighter II on Steam (Indie, Casual, Rhythm, Funny, and Local Multiplayer): closest matches first, and among equally close ones the better-known games.

Muse Dash
Shared: Rhythm · Casual · Great Soundtrack

Stick Fight: The Game
Shared: Funny · Local Multiplayer · 2D Fighter

Undertale
Shared: Great Soundtrack · Indie · Funny

Rivals of Aether
Shared: Indie · 2D Fighter · Local Multiplayer

Rhythm Doctor
Shared: Rhythm · Indie · Funny

Geometry Dash
Shared: Great Soundtrack · Rhythm · 2D

A Dance of Fire and Ice
Shared: Rhythm · Indie · Casual

Timberman
Shared: Casual · Indie · 2D

To the Moon
Shared: Indie · Great Soundtrack · Funny

Super Hexagon
Shared: Indie · Great Soundtrack · Rhythm

One Finger Death Punch
Shared: Indie · 2D Fighter · Casual

Pizza Tower
Shared: Indie · Great Soundtrack · Funny

Plants vs. Zombies GOTY Edition
Shared: Casual · Great Soundtrack · Funny

DELTARUNE
Shared: Great Soundtrack · Funny · Indie

Donut County
Shared: Indie · Casual · Funny

Just Shapes & Beats
Shared: Rhythm · Great Soundtrack · Indie

Lethal League
Shared: Indie · Local Multiplayer · Great Soundtrack

Gang Beasts
Shared: Funny · Casual · Local Multiplayer

Oh...Sir!! The Insult Simulator
Shared: Indie · Funny · Local Multiplayer

Montaro
Shared: Casual · Indie · Great Soundtrack

There Is No Game: Wrong Dimension
Shared: Indie · Casual · Funny

Audiosurf 2
Shared: Indie · Rhythm · Casual

OneShot
Shared: Indie · Great Soundtrack · Pixel Graphics

Duck Game
Shared: Funny · Local Multiplayer · Indie