Warpman is Namco's followup
to the 1981 arcade game Warp Warp. Unlike the previous game, Warpman
was never released in the US, but gameplay in both is very similar to
the point where Warpman is almost more of an upgrade than a sequel.
Gameplay takes place in two different worlds, Space World and Maze World.
Space World is a multidimensional fixed screen shooter where you're faced with a number of different alien enemies to destroy. Killing all of them brings you to the next level. This is pretty basic, even as far as mid-80s shooters go, though the enemies do offer some variation – including some that spawn clones of themselves.
At the center of the screen is a nebula-looking area that, when flashing, can transport you to Maze World – though note that you never have to enter it, and can, if you choose, play the entire game in Space World if you prefer that kind of gameplay.
I personally found Maze World more compelling, however... instead of a shooter, it plays like Bomberman – a game that Hudson Soft had introduced to Japan two years prior. It plays just as you'd imagine it to – you run around the maze, dropping bombs, blowing up the enemies.
Each stage contains both worlds, and you can pass between them back and forth until you've killed all the enemies. You're not compelled to, but an interesting gameplay twist is that each world will generate a weapon powerup that will make your gun or bomb more powerful in the other world, so it's worth giving it a go at least.
That said, there are better shooters than Space World, and if you want to play Bomberman Maze World is a poor substitute. The game is, to be blunt, plain, without a great deal to recommend it. I give it a D ranking.