Path of Exile. Fairly good hack 'n' slash with some interesting loot mechanics. There's no gold, just item modifiers - upgrade standard to magic, magic to rare, add an extra magic property etc. Also, refillable health flasks.
Most importantly, it's free, and I've yet to work out what I'm actually supposed to pay for, which is a good sign.
Give it a go and we'll beat up Dire Squid some time.
http://www.pathofexile.com/