The first thing you should know about the upcoming isometric, co-op, downloadable game Lara Croft and the Guardian of Light: This isn't your father's Tomb Raider. In fact, it's not even a Tomb Raider game at all -- notice those words conspicuously absent from the title.

Consider Guardian of Light to be a kind of appetizer for the Tomb Raider franchise, something to whet your appetite during the long development cycle between tent-pole Tomb Raider releases. It's the best thing to happen to Lara Croft in years.

This franchise appetizer strategy is being employed by more and more developers. The PSN download Ratchet and Clank Future: Quest for Booty bridged the gap between Tools of Destruction and A Crack in Time, engaging players in a brisk 4-6 hour story. And at GDC this year, THQ's Danny Bilson said that the company's "core brands" will get downloadable entries this year.

I can see why franchise appetizers appeal to game makers. With development costs ballooning and broadband penetrating more homes, why not take a chance with a $10 or $15 game? The games can reuse assets (Quest for Booty) or an engine (Guardian of Light) to keep costs low and development time brief.

Franchise appetizers can also function as proving grounds for new features. Shifting perspective and dropping in co-op in the next mega-budget Tomb Raider game would represent a huge financial risk for Crystal Dynamics and publisher Square Enix. But in a $15 "Lara Croft" game? It's pocket change. If Guardian of Light proves successful, don't be surprised to see co-op in the next iteration of Tomb Raider.

Best of all, these benefits trickle down to the player. For fans, a franchise appetizer can be a welcome dip into a favorite series. For other gamers, the radical changes to gameplay in the franchise appetizer may tempt them to try out a series they've otherwise avoided -- or bring back former fans who have strayed.

Take me, for example. I haven't been genuinely excited to play a Tomb Raider game since the original entries on the PS1. But as I sat through the Guardian of Light demo at GDC, all I wanted to do was grab the controller and jump in myself. I can't think of much higher praise than that.