Gridrunner Rev is the oft overlooked Llamasoft game. I sorta get why, it's not the most approachable despite being clearly designed -to be- the most approachable.
That said, it's a little hard to grasp as it exists in its own world and with its own language. Exploding suns, flowers, pretty colours yet really, it's a fairly straightforward game to play with a strong scoring mechanic. Essentially, the prettier a pattern you make on screen with your bullets, the higher you score. If nothing else, that's different, right?
If I had to pull it on anything it's that it locks the best part of the game behind an awful unlock system. You have to wade through a slow and slightly uninteresting group of stages before the high score mayhem can begin in earnest. Again, a clear attempt to draw people in but let's be realistic here, Gridrunner Rev is -for- the kind of people who really enjoy score chasing.
And y'know, when the whole screen explodes around you with the Neon effects in the background it's quite the sight to behold.
So yeah, a bit janky round the edges, attempts at accessibility that fall a little flat but a great underloved gem that given some time to gel makes for a good companion piece to Space Giraffe.