The first thing you'll notice is that there are a ton of different things added to the classic Halo formula.
To install SPV3, simply make sure you have Halo: CE installed and run the executable. A group has taken to remixing the original Halo, coming out with SPV3, a mod that completely remixes the campaign. However, its at time dated feeling does hold it back in some fan's eyes, as the Halo sandbox has evolved exponentially since then. People who never experienced it when it first came out will play it and scoff at how unoriginal and cliche it is - that's how much of an influence on the genre it had. Halo: Combat Evolved is one of the most influential first-person shooters of all time.
