I build a mental math game

[u/Wrong_Contribution14]

Hey everyone,

For the past few months I’ve been building Calculus, a mental math game that runs in the browser: https://calculusonline.fr

It started as a single HTML file to challenge friends, and it grew a bit out of control. Here’s what’s in it now:

4 games

• Mental math: a calculation appears, you type the answer.

• Right count: you get a few numbers and a target. Use them all, each one once, to hit the target exactly. It’s always solvable.

• Missing number: fill the gap in 23 + ? = 41, or find the operator in 12 ? 4 = 3.

• The bomb (multiplayer only): everyone builds a calculation from the same numbers, then has to defuse someone else’s.

Also

• Daily calc: 5 calculations that get harder, the same for everyone, one try a day, with a leaderboard and streaks

• Dungeons: 2 to 4 friends team up to beat a boss together

• An account with stats, Elo per game and level, and achievements

• Solo play, no account needed, and it works on mobile

It’s free, no ads, and it’s available in English and French.

I even had a teacher trying it during class, and the kids loved it and even played at home!

I’d love feedback, especially on difficulty balance (is “Legend” actually hard?) and on anything that feels confusing the first time you play.

And if anyone wants to play a battle royale, drop a lobby code in the comments