U61 in a nutshell

U61 is "another block-based game". Its main features are:

  • Network play. Gameplay should be fast even with poor bandwidth. Local multiplayer game is also available.
  • Theme support. The graphics and sounds are fully configurable.
  • Rules customization. As it uses Lua scripts, the game rules can be changed by any player, without having to modify any complex C++ code.
  • Cross-platform support. Since it is based on ClanLib, U61 runs on any platform supported by ClanLib (GNU/Linux, Windows...).

Basic rules

The basic rules in U61 are:

  • The player has a map, and blocks fall int it. Blocks are made of colored squares.
  • The player may control the block as it falls, for instance rotate or translate it.
  • When the block lands at the "bottom" of the map, ie when it can not fall any more, it is merged with the map.
  • When a given pattern is matched in the map, for instance, squares of the same color, then these squares explode and disappear.
  • There's always a special square on the map, and when this square explodes, a "curse" is activated. Curses can be anything from bonus to maledictions.

These rules are not very precise, and this is what makes U61 different from other block-based games: it is possible to create one's own rules and play with them. This is achieved by creating scripts, using the Lua language.

Hey, but this is a Tetris clone!

No! No and No!

U61 is *not* a Tetris(c) clone. Its rules are much more general.

It's true that when I first started the project (in 1999), its name was "Tetr61s" and it was supposed to look much like "EITTris" with network support. Since then, I've had to deal with the so-called "Tetris Company", and realized that cloning Tetris(c) is not possible anymore. So I decided to start a more general project, which name is U61. Of course it's possible to configure U61 so that it looks exaclty like the genuine Tetris(c). But such a configuration is not provided in the standard distribution (inded the "classic" set of rules includes many enhancements).

So Tetris(c) can in a way be considered as a subset of U61, but this does not mean at all that U61 is a Tetris(c) clone.

But if you liked Tetris(c), Columns(c), or Puyo-Puyo(c), then you should like U61, so try it!


U61 is distributed under the GNU General Public License (GPL).

This means U61 is free software. Free as in speech. You can use it, modify it, and distribute it freely as long as your modified product still respects the GPL. For more information about the GPL, see:

  • The "COPYING" file which should be present in every distribution of U61. It contains the GPL.
  • The GNU (Gnu's Not Unix) is the result of the work of the FSF (Free Software Fundation). It is an attempt to make a complete and free UNIX like OS.

Please note that even if U61 can be considered as Open Source (, I consider it as Free Software. So if you ever mention U61, please refer to it as being Free Software, and not plain Open Source.


As of today, I (Christian Mauduit) have written most of the code in U61. My coordinates are:

  Christian Mauduit
  Web site:
  GnuPG public key: FD409E94 -
  GnuPG fingerprint: 4762 1EBA 5FA3 E62F 299C  B0BB DE3F 2BCD FD40 9E94
  Snail mail: 32 rue Jean Moulin  95100 Argenteuil  FRANCE

Feel free to contact me, I always appreciate feedback.

An important contributer is Ursula Adler (U-Woman), who gracefully prepared the "default" theme for me. Please keep in mind that the graphics she prepared for me can be (and they are) released under the GPL, but her graphics are usually protected by other license agreements. Check her web site ( for more information. Please do not rip her graphics without asking.

Jimmy Kaplowitz wrote the "unstable" curse, and is currently works on Debian support for U61 - which is not an easy task since U61 has a bunch of dependencies 8-)

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Copyright © 2005 Christian Mauduit. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
Updated on Sun May 29 2005.