An editor of Wikipedia assessed Wikipedia's article about Tetris and gave it a C. Jappalang identified these issues, among others: Wikipedia is not a game guide. It doesn't need a list of the colors of tetrominoes in every pre-SRS game. It doesn't need an analysis of the difference between naive and recursive gravity. In general, it doesn't need in-depth discussion of game mechanics unless a mechanic has had a significant impact on the game's reception, as in the case of infinity in Tetris Worlds or the allegedly unbalanced T-spin reward in Tetris DS versus mode, or the mechanic has been subject to scholarly analysis, such as the ideal uniform uncorrelated randomizer that older games approximate. Ideally, each claim in an article should cite multiple sources, so that readers can verify that the sources are reliable. Does a source more mainstream than Vadim Gerasimov's own web site back up that he worked with Mr. Pajitnov to develop Tetris for MS-DOS? Tetrisconcept.com is not a reliable source. Blogs, forums, and publicly editable wikis are excluded from the definition of reliable sources. Therefore, every time the article cites Tetriswiki, it gets removed and replaced with , and someone else can just remove anything unreferenced. The official Wikipedia view on the topic is a composite of what reliable sources have published. For example, Wikipedia officially thinks that Tetris still uses the memoryless randomizer and therefore cannot be played forever because unlike "Tetris is hard, even to approximate", CT's "Playing forever" article hasn't been published in a scholarly journal.