Biniax

Biniax is a free and open-source puzzle video game which was first released in 2005. A sequel, Biniax-2, was released in 2007, with a more polished look and feel, and different game modes: arcade, tactic and multiplayer. The most recent release was in 2012.
Gameplay.
The gaming field is 5 × 7 pairs of elements. Every pair consists of two elements out of four possible types (colors). Player is a single element, who can move on empty fields or can take a pair, if the player's element is present in the pair. If a pair is taken, the player's element is swapped to the other element of the pair. The field is scrolling down on time event or after certain moves are spend (depending on the game mode). Game over is when there is no move for the player.
Examples.
In example below, the player [U] takes the pair with moving up and becomes [X].
Every new row consist of four pairs with one pair left empty random.
 .H-O X-U U-X O-U. .O-X H-X O-U U-X.
 . . -> .H-O X-U U-X O-U.
 . [U] . . [U] .
The player [U] takes the pair with moving up and becomes [X].
 .O-X H-X O-U U-X. .O-X H-X O-U U-X.
 .H-O X-U U-X O-U. -> .H-O [X] U-X O-U.
 . [U] . . .
When the field in front of the player is empty, the scrolling doesn't move the player's block.
 .H-O X-U U-X O-U. .O-X H-X O-U U-X.
 . [U] . -> .H-O [U] X-U U-X O-U.
 ... ...
When the pair in front of the player could not be taken, it pushes down the player's block.
 .H-O X-U U-X O-U. .O-X H-X O-U U-X.
 . [O] . -> .H-O X-U U-X O-U.
 . . . [O] .
When the pair in front of the player could be taken, the player stays at same position, automatically taking the pair.
 .H-O X-U U-X O-U. .O-X H-X O-U U-X.
 . [U] . -> .H-O [X] U-X O-U.
 ... ...
Ports and remakes.
There are 3 Biniax games – Biniax, Biniax-2 and BiniaxMobile. All the versions are open-source under the zlib license, first two are coded in C, and mobile version is in Java ME. The source code is available as zip from the website of the programmer. Latest version is from 2012.
The game is usually ported (Biniax-2 mainly), but some remakes exist (like Mojon Twin's version for 8 bit Sinclair ZX Spectrum).
Reception.
In 2008 Biniax-2 was awarded the 3rd place at the Bulgarian Computer Space 2008 festival in "Offline multimedia" category.
In 2008 a short feature of Biniax-2 in GameTunnel stated:"...it is definitely the kind of game you'll want to have around for anytime you have a free minute because it is absolutely fun!".
In 2007 a Bytten review of Biniax-2 rated the game with 70% overall score. Biniax-2 was review in 2007 by the Polish VictoryGames website and was awarded a silver medal.
FreeGameArchive described in 2007 Biniax mobile as: "Biniax Mobile is one of the best logical-express I've ever played on mobile phone!".
A review of Biniax-2 at PlneHry.cz in Czech in 2007 rated it 7/10.
An extensive review on "AllAboutSymbian" in 2005 for Biniax Mobile rated it 75/100.
Biniax was also included on several video game magazines' cover disks with freeware game compilations, and was part of the Open Source Software CD.
"Biniax" was selected in March 2016 as a "HotPick" by Linux Format.