For the major plot points, my story is almost identical to Hellfish's but I'll add a few individual details....
Stage 1: I have had the original CDs for the old Microprose game ever since it was new. The bad part: the game only contained very old cards and couldn't run (or more specifically, couldn't install) on any post-Win9x OS. I have an old Pentium III Windows 98 box mainly for the sole purpose of being able to play that game!
Stage 2: I get the Microprose MtG install & run on a VM. Not an easy task and it doesn't run perfectly (it gets 'stuck' every now and then) but it's the best computerized single-player adaption I know of. The good part: I can finally get rid of that old dusty P3 box. The bad part: The game doesn't run smoothly on a VM, and I'm still stuck with those ancient cards.
Stage 3: Googling the web for any patches (official or unofficial) or just about anything to add to the Microprose game, I first come across mtgrares' blog, and then this site. I discover Manalink. The good part: Manalink allows me to play the Microprose game on a modern computer without any silly virtual machines, and there are thousands of new cards! The bad part: The only game mode that works decently in the current ML3 is Constructed - which, unfortunately happens to be my least favorite mode for playing against the computer (except perhaps for testing a real Constructed deck). The Sealed Deck Mode works erratically at best. Shandalar has been removed into a separate game, and although there are several nice improvements, the lack of new cards in Shandalar was a showstopper for me. And to add insult to injury, Manalink has those 'locked' cards that you need to 'unlock' by completing challenges - until you do, they will be locked even in the Limited Mode!
I quickly lost interest in Manalink because of this, although I played the separate Shandalar game for a while and had a good time (my Blue starting pool had
The Hive and
Sunken City...I soon found
Alchor's Tomb, and lots of fun with a
Sunken City or two and multiple blue Wasp tokens. Not something I'd ever attempt in Constructed play! But it did work ok against the early Shandalar enemies).
Stage 4: Even though I love the Microprose UI (the most intuitive so far, and graphically very impressive), I don't want to play Constructed against a computer. Especially not single Constructed matches.
But wait, there's more...
The site has info on several unofficial MtG adaptions that allow you to play Sealed Deck against the computer. And they have lots more implemented cards than Shandalar!
I tried them all, and guess which one I liked the best...