I have always dreamed with a far-west role-playing game... and I found it. At the beginning - my current state :) - you work, get money to join or start a town, and fulfill the adventures - the funniest part- proposed by the sherif, an indian or the pub owner. It is possible to duel with other characters too, but it isnt needed if you are the peaceful guy :)
Free: You can buy advantages. Tottally playable without them though.
Time needed/day: from 5 to 45 minutes, it is your choice.