Games like Rampage Online
Games like Rampage Online include Notes of Soul, Tower Unite, Touhou Big Big Battle, Timberman, and Starblast. We matched them by the tags players give Rampage Online on Steam (Indie, Casual, Action, and Massively Multiplayer): closest matches first, and among equally close ones the better-known games.

Notes of Soul
Shared: Massively Multiplayer · Action · Indie

Tower Unite
Shared: Casual · Massively Multiplayer · Indie

Touhou Big Big Battle
Shared: Indie · Casual · Massively Multiplayer

Timberman
Shared: Casual · Indie · Action

Starblast
Shared: Action · Indie · Massively Multiplayer

Witch It
Shared: Casual · Indie · Action

ShellShock Live
Shared: Action · Casual · Indie

Pikuniku
Shared: Indie · Casual · Action

Dead Bits
Shared: Indie · Casual · Action

Last Oasis
Shared: Massively Multiplayer · Action · Indie

Gensokyo Night Festival
Shared: Indie · Action · Casual

One Finger Death Punch 2
Shared: Indie · Action · Casual

Retrowave
Shared: Indie · Casual · Action

Superflight
Shared: Indie · Casual · Action

Hide and Seek
Shared: Casual · Indie · Action

Timberman VS
Shared: Casual · Indie · Action

Infestation: The New Beginning
Shared: Massively Multiplayer · Action · Indie

Gang Beasts
Shared: Action · Casual · Indie

Cyberhunt
Shared: Indie · Casual · Action

Caster
Shared: Indie · Action · Casual

Minimalism
Shared: Indie · Casual · Action

Snakeybus
Shared: Indie · Casual · Action

One Finger Death Punch
Shared: Action · Indie · Casual

Yokai's Secret
Shared: Indie · Casual · Action