When people talk of "Total Conversions" of the Marathon universe, Trojan is one of the names that should come up first. Trojan is a complete replacement for the Marathon package-think of it as an action game that happens to use the Marathon engine. The artwork is superb, the new weapons are awesome, the baddies are frightening... and the full package is completed. Twenty-five levels of pulse-pounding excitement... don't pass it up. If you're using the version of M1 that comes on the Trilogy disc, you'll want to grab the Trojan/Trilogy Patch, as well. (It's only 35K.)