Not so sure about fieldrunners (only 3 maps) but galcon is definitely amazing. GET GALCON NOW!!! It involves strategy elements like Fire Emblem, but its real-time and fast-paced. Also, there's internet multiplayer
I totally disagree. It is one of my favorite games. If you are an impatient gamer who wants an instant fix with blood, guts and gore, it won't be for you. If you want a deep, fun involving game where it's in real time even as you sleep (if you don't put it on pause that is(, then this game is def long term.
I'd put in a second vote for Puzzle Quest. It's a fairly innovative idea (an RPG, but you fight battles by playing a match-3 puzzle game), and it can potentially take hours and hours.
The Quest, ElementalMonster TD (technically I don't yet but from what others say, it's very challenging and I love it), Hospital Havoc, Airplane Mania, Wolfenstein 3D (if you don't use cheat codes), Bookworm, Besiegement TD, Let's Golf. All have long term play.