There has never been a good Akira game. There have been bad ones, however, and more interestingly, there have been cancelled ones like this Game Boy effort, the remains of which were recently bought by a video game collector and are somewhat playable.
Patrick Scott Patterson managed to get his hands on not one but four copies of the game, each one featuring a build in various stages of completion, and has been able to play them and check out how much had been done before the game's cancellation.
It's rough, as you'd expect from an unfinished Game Boy title never intended for public display, but there's still enough going on to get a feel for the game.
There's a split between side-scrolling platforming and Excitebike-like driving sections, with one stage also having you fly a hovercraft. There is a lot of placeholder art here, sometimes covering entire stages, and the platforming in particular has only the most basic coding in place to get the character (well, characters, since you seem to control both Kaneda and Tetsuo) moving.
You can check it out below. WARNING: the placeholder game music may cause you harm.
In terms of other people getting to play this, Patterson says that he's got long-term plans to lift the best sections from each of the four builds, combine them and try to salvage something at least remotely playable for fans.