B+Main Assembly
A sophisticated toy-box sandbox where players build robots, vehicles, and contraptions using advanced engineering tools and a visual programming interface.
Parent verdict
Is Main Assembly good for kids?
Yes — a great pick for most kids
Rated Ages 10+. Best for problem-solving, patience.
Reviewed by Hess Polanco, parent tester & co-founder · Updated April 21, 2026
The busy-parent summary
Time required
20-60 minutes
Safety level
High
Best for
Problem-solving, patience
Ages
Ages 10+
Great for your child
It allows them to bring their wildest mechanical ideas to life with real physics and logic.
Great for you
It provides a clear platform for you to act as a consultant or 'co-engineer' on fun projects.
Parent notes
Moderate online interactions by using password-protected private servers for co-op. Remind children to take breaks, as deep technical building can lead to 'flow state' eye strain.
The Connection Grade™ breakdown
Four things we grade, each one judged on what this game actually does. Open any row to see why.
Co-op lets you build and test together on the same bot, but the visual programming interface is complex enough that one person often ends up doing the wiring while the other just watches.
Skills this builds
- Splitting roles between chassis framing and sensor wiring
- Troubleshooting why a steering axle locked up during a test drive
- Collaborative test-driving through obstacle courses you built together
Try this together
When the chassis rolls over on the first incline, let them steer while you adjust the center-of-mass slider together.
Parents also ask
Ready to play Main Assembly together?
Put it on the calendar and we'll send a reminder plus a conversation starter.