ComeSpaceX has the shell of what could be a great game. It excels where some other action games fall short. While in its current form it is not as strong as the excellent Sentry Alpha, it has some great features and promises to get better.
SpaceX begins with a spaceship taking on enemies in somewhat Galaga-style action. The ship is controlled with either your finger or by tilting the iPhone/iPod touch. The controls are quite responsive — the ship moves both from left to right and up and down on the screen so you can shoot enemies and snag upgrades that float across. But it is another aspect of the game play that weakens SpaceX. Most of the spaceships, even in the later rounds, speed toward you with guns blazing — so fast that it is impossible to get in front of them for a clear shot. This is less of a problem in deeper rounds when there are multiple lasers and missiles that will shoot from the side of your spaceship or track the enemy. In terms of controlling the ship it means a lot of back-and-forth movement to get a clear shot. A tweak to the enemy ship firing patterns would make the game play a bit more reasonable.
The strongest area of SpaceX is the upgradeable weapons. After each round you have the ability to purchase new weapons with game credits earned during the previous round. This part can get a bit tricky because you need to pay attention to where the weapons are mounted. Buy an upgrade that mounts in the same location as another weapon you already have and that one is gone. It is a bit of a pain, but with a better system for identifying what weapons are where this will be even stronger.
The developers indicated on the SpaceX iTunes description page they plan to update the game soon with bug fixes, touch controls, and better game balance. Hopefully they come through, because SpaceX is good enough to be worth making even better.