most people (including me) will not install a new program just to unpack your game that you uploaded in RAR format, because there’s 100 more games that they can already unpackage because they’re in the ZIP format, which can be unpackaged in any OS without having to install anything.
an alternate format like 7Z or RAR or TAR or TAR.GZ or TAR.BZ2 should not be the only way to download your game, but a bonus so that people who already have the right program can download the game faster than the standard ZIP version.