Whats a gaming failure or undeveloped project you wish had a more successful release/was fully realized? For me its tomb raider angel of darkness. There were a lot of problems with the production, ranging from lack of leadership to scrapped concepts to the unpreparedness of the team for the complexity of programming for the PS2. Core design didnt have enough time to iron out the kinks even with all the crunch time, and eidos didnt give them more time because they wanted to release in june.
The game was an unfinished mess, full of bugs and haphazard level design. But its gained something of a cult status within the raider community, with memes centering on its iconic side characters like janice the parisian sex worker as well as lara's feisty one-liners. Its still being kept alive by a dedicated community of speedrunners and unofficial remasters. I often think what could have been if it had more time to at least be passable at launch. Core planned two sequels that would have continued the story. Obviously they were scrapped, core design went defunct, and tomb raider was handed over to crystal dynamics.
Right now, I can think of a couple that probably only I care about. The first is that shmup Treasure were supposedly developing for the Xbox 360 that never came out and there's almost no information on it
The second one is even more obscure, but I wish Taito had stuck with the 2D pixel art for the second game in the Ray* series. There's a one level prototype called R-Gear which is done in 2D pixel art, which annoyingly isn't available in the recent collection unless you got some Japanese physical limited edition Switch release. RayStorm is a good game, but RayForce just has such beautiful pixel art and I want more of that