Maybe I'm more of an "old school" gamer than Mike is, but I appreciated Serious Sam a bit more than he did. I found the game's 36-mission campaign to be more than a simple Doom rehash. Certainly there were moments when I felt a twinge of the old Doom nostalgia (I was a Doom-addict in graduate school), but dismissing Serious Sam as little more than a Doom clone isn't giving the game the credit it deserves.
I absolutely agree with Mike that Serious Sam doesn't represent the apex of the first-person genre—Halo currently wears that crown, with Metroid Prime coming in a close second. But Serious Sam isn't the least bit interested in furthering the genre. It's intended to be more homage than evolution. The game wants to pay tribute to ancestors like Doom and Duke Nuke 'Em, and it does so by exploiting every last cliche of the first-person genre. Early in the game, a monster suddenly materializes in front of Sam and gives chase. While performing the ubiquitious backpedal-and-shoot move that I've been doing in these games for years, Sam says, "I hate running backwards." The genre cliche is duly acknowledged even as the game exploits it--and this is the real genius of Serious Sam. The game in fact does so much cliche-acknowledging that it nearly breaks into full-blown parody, and it probably would be considered parody, if it wasn't so much damn fun to play.
While the venerable Doom certainly provided its fair share of thrilling moments, there's nothing in that game that could have prepared me for the size and scope of the epic battles found in Serious Sam. I was, quite literally, one man versus an army. I haven't dealt with this kind of adversity in a videogame since Smash TV on the Super Nintendo. In fact, Serious Sam, with its seemingly endless onslaught of enemies, arguably has more in common with Smash TV than Doom. Just when I couldn't take anymore, when all of my weapons were low on ammo and my health points were dwindling, yet another legion of ghouls appears on the horizon. What did I do? I dove right in, of course. This is the moment when Serious Sam transcends the genre; as the battle escalates in ways that are so outrageously over the top (dive-bombing bikini-wearing hawks, screaming kamikaze bombers, rocket-launching mechs, charging wild bulls) I was laughing at the absurdity of the action even as I gritted my teeth and blasted for my life. And this is the moment that distinguishes Serious Sam from the other Doom-clones out there. Yes, we've all played this before, but never quite on this scale.
While the enemy A.I., as Mike states, is certainly lacking, the monsters are so diverse, and require such varied strategies to defeat, I actually had to use my intelligence in order to survive beyond the first few levels. Rushing into combat with my chainsaw blazing only got me killed in a hurry. I constantly needed to draw up strategies on the fly, deciding which weapons to use and where to place myself geographically, especially on the Hard and Serious difficulty settings. No, it doesn't have the "depth and subtlety" of Halo, but after spending a few hours with Serious Sam, I found it to be deeper and richer than I'd previously thought.
After finishing Metroid Prime a few days ago, Serious Sam was an utter pleasure for me to play. No more platform-jumping or visor-switching or enemy-scanning was necessary; I actually appreciated the simpler, more visceral gameplay of Serious Sam. And the game feels much also more irreverent and playful than Metroid Prime, or any other game in the genre for that matter. Serious Sam is a simple game that doesn't try to do too many things, and the few things it sets out to do, it does quite well. The game truly has an excellent sense of itself.
Though it doesn't necessarily advance the genre in any notable way, Serious Sam is always fast, always fierce, and always fun. It's the ultimate twitch-shooter. At a time when first-person games are evolving—which, for the record, I'm all for—it's still great fun to be able to roll up my sleeves and relish some honest-to-goodness, blood-and-guts gameplay. And Serious Sam delivers that in spades.