Battlezone has been around for just shy of forever, and was one of the games leading the charge back in early days of the arcade. A mere two years younger than Space Invaders, it was released in 1980 with lovely vector graphics and a twin-joystick control method. Since then it's had two action/strategy sequels on PC and a straight-up action version on N64, and now the PSP gets a crack at the name.
The quick verdict is that the first PC game is still the single greatest Battlezone ever made, but very few games can top that, so that's hardly a put-down. Battlezone PSP is a handheld conglomeration of several popular online play types using giant tanks. Deathmatch, team deathmatch, capture the flag, capture the glowy-ball and try not to get killed, and a couple of others to round things out. Playing through Campaign Mode yields a nice variety of objectives as it cycles through the various game formats and arenas, but it's so short and easy that it can be beaten in a few sittings.
Battlezone is hamstrung by its camera, control, single-player ease, and lack of online support, so it just falls apart in the end.
That's the least of Battlezone's problems, though. The tanks hover above the ground, floating along at the whim of inertia and terrain, and maintaining control can be a matter of wishful thinking at times. This isn't helped any by a camera that delights in getting caught on walls, giving you a great view of the tank's underside while enemies pour on the firepower. Despite the extra-floaty controls and spastic camera, though, it's still pretty easy to pull out a victory even on Veteran difficult. A little bit of control, a decent weapon loadout, and the right tweaks (stat enhancers earned in the Campaign mode) guarantee a win ever time.
It's pretty obvious that Battlezone is designed with multiplayer in mind, but finding someone with a copy of the game, much less three other people for a real match, is going to be tricky at best. The online options are limited to a level editor that allows for a few items to be scattered around a preset arena, with no actual online play, so Battlezone ends up as a multiplayer game with very low odds of going up against another human.
It's a shame, too, because there could be a solid game hiding under all those issues. A good graphics engine powers everything, the three tanks classes all have different weapon selections to go with the usual armor and speed differences, and the entire game has a feeling of "almost" about it. It's almost good, has the potential to be fun, and could have been worth the effort. But Battlezone is hamstrung by its camera, control, single-player ease, and lack of online support, so it just falls apart in the end.