Games like Synthetic Paradox
Games like Synthetic Paradox include Risk of Rain 2, Gunfire Reborn, Ravenswatch, The Spell Brigade, and SYNTHETIK: Legion Rising. We matched them by the tags players give Synthetic Paradox on Steam (Tower Defense, Roguelite, Roguelike, Online Co-Op, and Action Roguelike): closest matches first, and among equally close ones the better-known games.

Risk of Rain 2
Shared: Co-op · Action Roguelike · Roguelike

Gunfire Reborn
Shared: Roguelite · Roguelike · Co-op

Ravenswatch
Shared: Co-op · Roguelike · Online Co-Op

The Spell Brigade
Shared: Roguelite · Online Co-Op · Co-op

SYNTHETIK: Legion Rising
Shared: Roguelite · Co-op · Online Co-Op

Heroes of Hammerwatch
Shared: Roguelite · Co-op · Action Roguelike

Children of Morta
Shared: Roguelike · Multiplayer · Online Co-Op

Streets of Rogue
Shared: Roguelite · Action Roguelike · Roguelike

ELDEN RING NIGHTREIGN
Shared: Co-op · Online Co-Op · Roguelike

Enter the Gungeon
Shared: Roguelike · Action Roguelike · Co-op

Roboquest
Shared: Roguelite · Co-op · Action Roguelike

HELLDIVERS™ 2
Shared: Online Co-Op · Co-op · Multiplayer

Brotato
Shared: Roguelike · Action Roguelike · Roguelite

Ember Knights
Shared: Co-op · Roguelite · Action Roguelike

Sephiria
Shared: Roguelite · Co-op · Roguelike

Risk of Rain (2013)
Shared: Roguelike · Action Roguelike · Online Co-Op

Bloons TD 6
Shared: Tower Defense · Co-op · Online Co-Op

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

BALL x PIT
Shared: Roguelite · Roguelike · Action Roguelike

Ship of Fools
Shared: Roguelite · Online Co-Op · Co-op

Wizard of Legend
Shared: Roguelike · Action Roguelike · Roguelite

Hades
Shared: Roguelite · Action Roguelike · Roguelike

Nuclear Throne
Shared: Roguelike · Action Roguelike · Roguelite

ANVIL
Shared: Online Co-Op · Action Roguelike · Roguelike