Q.U.B.E. (found betas of PC puzzle game; 2010-2011)
Quick Understanding of Block Extrusion (Q.U.B.E.) is an independent first-person puzzle game released for the PC on December 17th, 2011, A director's cut for the game released on PC and other platforms in 2015, and a sequel, Q.U.B.E. 2, was released on March 13th, 2018.
The game takes place in a sterile environment similar to that of Portal, with the player's character waking up equipped with high-tech gloves which are able to manipulate and extrude color-coded cubes in the environment.
Q.U.B.E. was developed by Toxic Games and originated as a student project. The developers had an IndieDB page to post news and beta versions of the game when they became available. Some footage of these betas have been released on YouTube at the time that they were available, but at some point after the game's official release, the developers removed the beta versions off their IndieDB page.
For some unknown reason, the files are not able to be downloaded via the Internet Archive, and there could be more beta versions of the game that aren't preserved.