Should I buy HL2 Deathmatch?

I've sunk 600-700 hours into the game, from 2005 to 2007. It's a very skill based shooter. You'll most likely suck a lot at the start - even if you're good at shooting, you'll want better movement techniques to survive. It really gets better when you learn how to strafe jump, bunny hop, grav-nade, grav-orb, etc. The most fun I had by far was in the tf2-ported capture the flag maps. Actually, the coop maps are also quite fun - think 32 players on a single map, serious sam style against the AI. There are also plenty of puzzle/platforming-like jump maps that can be quite a time sink as well.

Yet, at this point it's so dated that I would recommend against buying it.

I would say yes. I once played for like 3 hours followed and had fun but beware of people killing you with flying grenades.

Like if he is going to make maps....