Do NOT say 21!

Turn-based arithmetic puzzle where saying the last number means losing

&y · Published by S Tier Garbage · Released Sep 19, 2025

Reviews: Very Positive; 83% of 71
Recent reviews: Not enough recent
Players: 0; daily peak, Oct 28, 2026
Steam Deck: Untested
Last update on Steam: 1 year ago; Sep 18, 2025
Minimum PC: You need one; 0.5 GB RAM · 0.1 GB disk; Full requirements

What is Do NOT say 21!?

This free single-player counting game pits you against Layla, a bored girl looking for someone to play with. You take turns counting upward in groups of up to three numbers, using the spacebar on your turn and trying not to say 21. Beating her three times in a row earns an achievement.

For you if...

+you enjoy arithmetic puzzles rather than reflex-based challenges

Not for you if...

−you want to compete directly against other players

What players say

83% of 71 reviews are positive

Players praise the simple premise as an entertaining brainteaser. Critics object to the use of generative AI and say there is little to do once the winning strategy is clear.

Screenshots and trailer

Do NOT say 21! system requirements

Minimum: You need one, 0.5 GB RAM, 0.1 GB of disk space.

As published by the developer.

Can my PC run Do NOT say 21!?

The published requirements do not name a graphics card we can compare.

Set up my PC →

Minimum

OS: Windows XP
Graphics: You need one
Memory: 512 MB RAM
Storage: 100 MB available space

Does Do NOT say 21! have co-op or multiplayer?

No: single-player only, no multiplayer modes declared.

Single-player

Does Do NOT say 21! run on Steam Deck?

Untested Not yet tested by Valve on Steam Deck.

PC version details

DRM: None declared on Steam
Controller: Keyboard and mouse
Platforms: Windows
Achievements: 3
Steam features: Family Sharing
Languages: Full audio: English.

Does Do NOT say 21! use AI-generated content?

Yes. The developers disclose AI-generated content on the game's Steam page:

The artwork, box art, voice acting and store page translation for this game was created with generative AI. The music is purchased from a stock website. The game’s code and trailer script was written by me without the help of AI.

The statement mentions: VoicesText & translationsStore page & marketing

Self-reported by the developer under Steam rules: it covers AI content that ships in the game, not tools used to make it. Steam page checked on Oct 27, 2026. How to filter AI games on Steam