What is the best steam game $10 or down?

I would highly recommend waiting for sales. During summer many games are 60-80% off and they can be bought for less than 5$. I would also recommend any of the Total war games as they are a very fun strategy series. Hope this helped

There are a good variety of games for 10 dollars on Steam. Try these:
Counter-Strike (original) - comes with Counter-Strike: Condition Zero for free (Multiplayer only)
Half-Life 2 - Comes with Half-Life: Lost Coast for free (15 minutes long story mode)
Star Wars: Battlefront 2
Half-Life: Opposing Force - 5 dollars on Steam
Half-Life: Blue Shift - 5 dollars on Steam
Half-Life (original) - 10 dollars on Steam
Mass Effect (original) - On Steam for 5 dollars on Steam in summer sale
Mass Effect 2 - 5 dollars on Steam in summer sale
Faltout 2 - 2.49 dollars on Steam summer sale
Day Of Defeat (original) - 5 dollars on Steam
Aliens vs. Predator 2000 Classic - 5 dollars on Steam