Similar to Hover Strike and Air Cars, you take control of a land-based vehicle, roaming the terrain blasting away at various enemy ships. The landscape would be barren if not for the ridiculous number of trees which can easily be set aside by shooting them down. There's also some small hills (more like bumps) and rivers that you'll cross along the way, but they don't factor into the gameplay or strategy in any way.
When you blow up trees or shoot down opposing vehicles, they go up in flames, except that the flames (perhaps realistically) remain on the screen for a very long period of time. In fact, the fire burns for such an inordinate amount of time that it becomes difficult to see anything because all you see are blazes of fire everywhere. Control is loose and floaty as was the case in Hover Strike and Air Cars, making it a chore to align your vehicle properly to attack enemy forces.
And if that's not enough of an indication that Phase Zero had a long way to go before completion, the version that I tried seemed to crash every so often, most prominently during the fourth stage. It just suddenly locks up without any warning. Of course, this isn't the only game that I've experienced that locked-up on the Jaguar (Doom and I-War come to mind).
Even taking to account that it's an unfinished prototype, Phase Zero is very rough around the edges. Hyper Image would've had to do a complete overhaul of the game engine if it were to be a smooth and polished combat game. That's not to say that the developers couldn't have miraculously turned the game around, but it's a moot point now anyways.