You have ten minutes between tasks and want a quick puzzle round against a real opponent. TETR.IO, made by osk, is a Windows game in the tetrisclone and tetrislike family that runs online and also supports singleplayer.
What an online stacker covers
The game is a falling-block puzzle built around stacking, and its store line calls it modern yet familiar. That suits players who know the genre and want to play it against others instead of alone.
Its tags list both singleplayer and online multiplayer, so it works for solo practice as well as matches.
Version 10.0.0 and the osk release
The current version is 10.0.0, last updated on October 21, 2025. The package ID is osk.tetr, and the app carries a copyright line for osk dated 2025.
The app is free.
Before you install the 87.8 MB download
The Windows download is 87.8 MB and comes straight from the official TETR.IO server at tetr.io.
Since the game is built around online multiplayer, a stable connection matters. For offline puzzling, kmahjongg, FreeCellOK and MineSweeperOK are among the alternatives worth a look.
TETR.IO pros and cons
Pros
- Free, with the price listed as 0
- Supports both singleplayer and online multiplayer
- Download comes from the official host tetr.io
- Small enough at 87.8 MB for most drives
Cons
- Little visual material to preview before installing
- Feature details are limited to a single line
- Online play depends on a connection
Is TETR.IO safe?
Get the file only from tetr.io, the address run by the developer osk, whose copyright notice is dated 2025. Our own servers do not carry the installer, so a copy from any other site is not the one we point to.
How to install TETR.IO
- Press the download button to get the official file.
- Run the installer you saved and confirm the Windows security prompt if the publisher matches.
- Follow the setup steps, then start TETR.IO from the Start menu.
