I've always enjoyed adventure games and I recently found two that were a lot of fun:
'Ben there, Dan That!' and 'Time Gentlemen, Please!'
Ben there, dan that! is FREE to download so give it a shot to see if you like it. You basically get captured by aliens and have to escape. I really liked the sense of humour as they poked fun at many adventure game norms. The puzzles are pretty fair too. Yes, the graphics aren't great but they did a surprisingly good job at drawing me into the world - personally, I think it fits the atmosphere very well.
http://www.zombie-cow.com/?page_id=17
yes, alternate universe nazis use a coathanger for their symbol
Time Gentlemen, Please! is the sequel and I think they did some really cool stuff (game within a game, time travel oddities). The story's pretty ridiculous - you're fighting against Hitler and his dinosaur army in an alternate world haha. You can buy the bundle on steam for 5 bucks so it's not a huge investment and it helps support these indie developers!
Steam store: http://store.steampowered.com/app/37400/
developer site: http://www.zombie-cow.com/?page_id=559
zomg, adventure game reference
The developers have some other games on there that might be cool too. I haven't really checked them out.
So if you like old-school adventure games, be sure to check this out! And support the developers by paying the bundle!
EDIT: added some pictures... hrm, i wonder if this could be moved into sports & games for some more exposure?