- 2+players
- PC
Commander, customize and build your Mechanical Assault Skeleton Suit (M.A.S.S.) and lead the fight against an alien invasion bent on exterminating the human race. The fate of humanity is in your hands.
Who can play
Store (how we check facts)- Split-screen is not confirmed.
- Online on PC. How many can join is not confirmed.
- Whether one copy is enough is not confirmed.
How it plays
Is it good
85%
Very positive on Steam
Steam Deck Playable
Every way to play together
Steam lists online co-op for PC. Player counts are not confirmed yet. 85% positive of 3,700 Steam reviews.
- 2+
Quick facts
- Developer
- Vermillion Digital
- Publisher
- Sekai Project
- Platforms
- PC
- Released
- Sep 15, 2025 on PC
- Controllers
- Full controller support on PC
- Languages
- Text in 5 languages
In these lists
Answers
- Does M.A.S.S. Builder have couch co-op?
- No same-screen play is confirmed. The Steam listing does not include it on PC. Online play is the way to play it together.
- Do you need two copies of M.A.S.S. Builder?
- No one-copy option is listed, so expect each player online to need their own copy.
- Does M.A.S.S. Builder work on Steam Deck?
- Yes, with some extra steps: Steam rates it Playable for Steam Deck.
- Is M.A.S.S. Builder free?
- No, it's a paid game.
