My computer program Forge lets you play the card game Magic: The Gathering against a computer opponent using all of the rules. This is very different than playing solitare Magic with Apprentice or Magic Workstation because the AI will attack and play spells. Currently there are over 1,800 cards ranging from old power cards like Ancestral Recall and Lightning Bolt to newer cards like planeswalkers. The user interface is basic, but it does let you download all of the cards pictures and view them while playing the game.
(If you don't know Magic, the easiest way to learn is to download this demo from here or here for Windows, it is 85 MB. Also checkout the YouTube videos at playmagic.com.)
You can also play sealed deck, draft, or the new quest mode. In draft mode the AI drafts for the 7 other opponents and builds the decks from the cards that it chooses. In the quest mode you start out with a few cards and the more games that you play the more that you win. As you get more cards you can update and change your deck.
There is also a "quest mode" where you start out with a small, random cardpool and you win more cards by playing against opponents. This is a scaled down version of Shandalar that is only menu based. On easy mode your goal is to win 10 matches. Easy mode is well easy because you always win cards after the match whether you win or lose. On some of the harder modes you only win cards if you win. Quest mode is challenging since the computer uses cards that are better than the stinky ones that you have. The computer opponents are divided into three categories so they get progressively harder.
Forge supports a number of keywords such as exalted, fear, flying, shadow, flanking, protection, wither, flash, defender, reach, and haste. Forge now also has a mana pool and supports creature enchantments.
The AI is very simple and does the best that it can. It tries to do reasonable actions. Sometimes the computer seems smart and sometimes it doesn't. Truthfully the AI plays random cards from its hand and each card has some AI code programmed into it. The computer can play cards like Counterspell but in all other cases the computer will never respond to a spell or ability on the stack. Also the computer will only play spells during its Main phase.
Forge runs on Windows, Linux, and Macs. You can download Forge from the panel on the right.
If you need to download Java, you can get it from here.