Gamitopia have published a review of Serious Sam. Heres a snip:
When I first fired up Serious Sam, I was quite honestly not sure what to expect. After playing for a few hours, however, I found that I was quite surprised at what Croteam had developed. In the game, you play Sam Stone, the last hope for mankind and set on a mission to stop an alien threat from wiping out the entire human race. By going through a Timelock device that scientists have discovered, you are sent five thousand years into the past (ancient Egypt to be precise) where you will attempt to stop them. From there the story evolves somewhat but it's not what makes this game so interesting.