M.A.S.S. Builder
Mech action RPG about building suits to fight alien hordes
Vermillion Digital · Published by Sekai Project · Released Sep 14, 2025
- Reviews
- Very Positive
- 85% of 4,125
- Recent reviews
- Mixed
- 50% of 12 in 30 days
- Playing now
- 13
- right now
- Steam Deck
- Playable
- Last update
- 1 year ago
- Aug 3, 2025
Free demo available, 1 playing it now: get the demo.
What is M.A.S.S. Builder?
An action RPG set in a future where alien beasts have driven humanity into shelters. You command a private military company, customize a mech and its weapons, and use boosters to move through battles against hordes of Quarks and larger enemies. Armor appearance and combat stats are customized separately.
For you if...
- +you like customizing mechs down to small visual details
- +you enjoy fighting hordes with a mech you designed
Not for you if...
- −you want a story-focused campaign more than mech building
What players say
85% of 4,125 reviews are positive · 50% of 12 in the last 30 days
Players praise the range of options for customizing mech and weapon appearances. Many say the combat feels clunky and repetitive, with ranged weapons weaker than melee, and some find unlocking parts grind-heavy.
Screenshots and trailer
M.A.S.S. Builder system requirements
As published by the developer.
Minimum
- OS
- Windows 7, Windows 8.1, Windows 10 (64-bit versions only)
- Processor
- Intel Core i5 or better / AMD Phenom II X3 or better
- Graphics
- NVIDIA GeForce GTX 1050 or better / AMD Radeon RX 560 or better
- Memory
- 8 GB RAM
- Storage
- 3 GB available space
Recommended
Requires a 64-bit processor and operating system
PC version details
DRM, required accounts, controller support and Steam features.
- DRM
- None declared on Steam
- Controller
- Full controller support
- Platforms
- Windows
- Steam features
- Cloud saves, Family Sharing
Steam Deck: Playable
- The launcher or setup tool may need the touchscreen or virtual keyboard
- Some text entry requires manually opening the on-screen keyboard
- All functionality is accessible with the default controller configuration
- Shows Steam Deck controller icons
- In-game text is legible on Steam Deck
- Default graphics settings perform well on Steam Deck
Multiplayer and co-op
Languages
Text only: English, Japanese, Simplified Chinese, Thai, Traditional Chinese.
Tags
- Mechs
- Action RPG
- Character Customization
- Robots
- Gun Customization
- Indie
- Hack and Slash
- Sci-fi
- Anime
- Shooter
- Action
- Singleplayer
- RPG
- Futuristic
- Multiplayer
- Third-Person Shooter
Recent updates
- Aug 3, 2025 · Incoming Patch Status Update
- Mar 2, 2025 · 0.13.0 Progress update
- Nov 30, 2024 · Patch 0.12.0 Released!
- Nov 28, 2024 · Upcoming Updates and Patch Notes
- Nov 10, 2024 · WIP: Update TImeline
1 DLC available.
