It's been 15 years since Croteam released the frenzied FPS Serious Sam: The First Encounter, a bit of trivia the studio brought up today that makes me feel really, really old. On the upside, it also announced that to mark the moment, which occurs more precisely on March 21, it's adding Steam trading cards to Serious Sam HD: The First Encounter, and its Second Encounter sequel.

It looks like there will be 16 cards in total, eight for the first game and another eight for the second. Most of the favorites seem to be here, although I'm disappointed by the absence of the Sirian Werebull. And—wait a minute—no Gnaar, either? Who came up with this list?

The HD releases on Steam are actually remakes of the first two Serious Sam games that were released on Steam in 2009 and 2010 with updated graphics and improved performance. The originals (also updated, but by fans—it all gets a little confusing) are still available, if that's your thing, as Serious Sam Classics: Revolution, but that won't get you the Steam cards.

Both the HD and the Classic versions, along with Serious Sam 2, Serious Sam 3: BFE, the Legend of the Beast, Jewel of the Nile and Bonus Pack DLCs, Serious Sam: The Random Encounter, and Serious Sam Double D XXL are available as part of the Serious Sam Complete Pack, which is on sale for 90 percent off—that's $10/£7—until March 22. Croteam also said, almost as an afterthought, that yes, it is still working on Serious Sam 4.