If you have never played Serious Sam, or if you played the original, there is an HD remake available (the same game, with WAY updated graffix on a new engine), and this month there will be The Second Encounter released.
The HD demo includes:
1 full level of the SP game
Coop gameplay
Death Match MP play
You can get it here:
http://store.steampowered.com/app/41020/
If you dont know what SS is all about, it is a throwback game of the fast and furious, billions of enemies at once, adrenaline pumping action type of gameplay.
Set in Egypt.
Aliens.
Laser gun (plus all the other weapons: Knife, Dual Pistols, ShotGun, Double Barelled SG, Machine Gun, Gatlin Machine Gun, Rocket Launcher).
Frenetic pace.
Lots of secrets (including secret levels).
Unique enemies.
Flying saucers.
A great old school game.

The demo also includes achievements--at least according to the store page--which is unusual for demos, so that's nice if you care about those.
I'm downloading it now.

Let us know how you liked it.
I loved it and bought it.
Will be buying SS TSE HD also.
:D

I hate the game.
I can't stand it at all.
I am new to the series and find the game so terrible that I will never play it, or it's sequels.

Dont hold back Wec, let us know how you really feel.
:P
What exactly didnt you like?

Dude, you don't want to know how he really feels.
Anyway, I'm downloading this too, mostly in time for the Second Encounter and if I like what I see I'll pick the game up retail or something. (Yes, I know it uses Steamworks anyway)

I haven't played the remake but the first one was loads of fun. Does HD change anything besides graphics?

Sigh. Still a Steam exclusive? Pass.

Duke Nukem, Unreal Gold, and Serious Sam.
Those were the days.

Okay, so if you like the demo you can buy the game and it will unlock the demo into the full version. Explains why it shows achievements.

The only things changed are this:
1. Graffix: much better. :)
2. No anti-gravity sections. They didnt take the rooms out, but they changed them: one is now upside down water, one is normal.
3. There are a few more secrets than the original. I think 3-4 more secrets.
Thats it.
The rest is all original.
Cant.
They dont have retail dvd's.
:(
It sucks, I know.
I was going to buy retail disk when it came out too, even though I bought digital also.
But, I think only germany got retail disks.

Yep.
The 1gb demo is actually the whole game.
Dont have to download anything else when you buy it.

It's okay if you're into old school no frills shooters but I don't think it's worth the price tag. $10 tops. They are remaking the second encounter so chances are they'll package them together in a couple of months.

It seems every other week it is on sale for $6.99 or $9.99.
Definitely worth it too.

I'll wait for a First + Second Encounter bundle before plunking down my cash-basically Serious Sam Gold HD.
That said, it does run great on my system.