Online co-op Diplomacy games

Every online co-op Diplomacy game on Steam we know of, newest first. Add tags or a price band to narrow it down.

Showing 1–10 of 19 games matching Diplomacy Β· updated 12 Oct 2026

Filters: Diplomacy Γ— Clear all
$
Released
Price
$ Β· Cheap
Players
πŸ‘₯ 1–4 players
Reviews
100% of 4

Fast real-time space conquest for 1-4 players. Capture planets, launch missile salvos, and outmaneuver friends in 10-minute Deathmatch blitzes β€” or scheme through 30 minutes of diplomacy, trade and betrayal in Hegemony mode. Cross-play with mobile; bots fill empty seats so a match always starts.

$
Released
Price
$ Β· Cheap
Players
πŸ‘₯ Not stated
Reviews
100% of 2

Develop your nation, command your army, and dominate the world in a real-time strategy game combining economic management, diplomacy, technological progress, and military conquest.

$$
Released
Price
$$ Β· Standard
Players
πŸ‘₯ Up to 8 players
Reviews
75% of 96

Lead any of 221 countries through a living 2026 world in this data-driven grand strategy game. Shape economies, politics and alliances, wage conventional or nuclear war, run covert operations, and rewrite the global orderβ€”alone or online with up to seven friends.

$
Released
Price
$ Β· Cheap
Players
πŸ‘₯ 3–16 players

Enter BETRAYED, a chaotic 3–16 player party shooter where trust collapses, lies spread fast, and paranoia turns friends into enemies. Use proximity voice chat to manipulate the room, earn Blood Credits for deadly traitor tools, and make every round end in suspicion, chaos, and betrayal.

If you loved these, you'll love this

$
Released
Price
$ Β· Cheap
Players
πŸ‘₯ Not stated
Reviews
92% of 115

Riftborne is a classic terminal based,Β real time, grand strategy game. Construct space ships. Take part in factional warfare. Hire galactic hit-men on your rivals. Raid neighbors for rare resources. Train spies to infiltrate enemy bases for key intel. Grow your empire to dominate the galaxy.

$$$
Released
Price
$$$ Β· Expensive
Players
πŸ‘₯ Not stated
Reviews
66% of 24,623

Use war, trade or diplomacy to satisfy your grandest ambitions and dominate five centuries of history in the newest version of Europa Universalis, Paradox Interactive's flagship historical grand strategy game.

$$
Released
Price
$$ Β· Standard
Players
πŸ‘₯ Not stated
Reviews
84% of 485

An approachable turn-based grand strategy sandbox. Lead a nation, forge alliances, wage wars and rewrite history. Play solo or with friends, create your own maps and scenarios, and explore community mods on Steam Workshop.

Free
Released
Price
Free
Players
πŸ‘₯ Not stated
Reviews
81% of 70

A love letter to old-school browser-based RTS MMOs – with charming nostalgic pixel graphics, a dash of political satire, and tonnes of strategic tension. Build your empire, face off against other players, and take what’s yours in true British imperial style: by dominating the map.

If you loved these, you'll love this

Free
Released
Price
Free
Players
πŸ‘₯ Not stated
Reviews
76% of 5,056

Fantasy comes alive in this vast yet cozy free-to-play MMORPG! Choose between 4 classes and 8 subclasses, explore hundreds of locations, thousands of quests, dive into varied PvE and PvP modes, enter the unique vibrant world, and trade with other players. Play, explore, fight and be victorious!