I've recently discovered the PC game
Dominion.net. As the name suggests, it is a copy of the game Dominion coded in .net with all the expansions included. Its only single player, but the AI is surprisingly good for a fan game like this.
The rules can be found
here, but essentially the game is card drafting. You start off with a deck of 10 cards - 7 copper and 3 1vp cards. There are 10 randomly selected cards you can buy on the table, and there are 10 of each of those cards. There are also stacks of copper, silver and gold which you can buy, and 1, 3 and 6VP cards you can buy.
On your turn you start off with one action and one buy. An action is essentially playing a card, and doing what the card says. They can give you more actions, more buys, more coins for the round, and many other things. Once you have no more action cards to play (Or no more actions to play them) you play all the treasure cards you have, and use the money they generate to buy a card from the table. Then you discard everything left in your hand and draw 5 cards, and your turn is over and the next person plays. If you don't have any cards to draw, you just shuffle the discard pile and draw from that deck again.
The game ends when either 4 of the stacks of cards have been emptied, or the highest VP stack of cards is empty. VP cards are important because obviously they are what you use to score, but they are also essentially wasted space. You win simply by having them in your deck, but when you draw them into your hand, they are a dead card. You can't play them, they aren't worth money to buy more cards with, they just get discarded at the end of the turn, taking up a space which could have had something more useful in. But equally, you need the cards to win. So you have to make the balance between having useful cards in your deck while making sure you have enough VPs in your deck to win. Its a very interesting balancing act, and the game plays out very well.
And despite being a relatively simple game once you understand the rules, there are so many different action cards that can be chosen to form the 10 available on the table to buy, it means that every game is going to be different due to different combinations of cards available to buy. Some interact really well together, some are a real pain.