My first experience with MTG was probably 20 years ago when a friend in our roleplaying gaming group bought a couple of self made small decks to show us that card game stuff.
Fortunately for our wallets , that card game didn't hooked us at all for some reason, it didn't even triggered my interest.
Years later, Microprose released Magic the Gathering that was a great card battle game, setup with the Shandalar plane in which you explored in real time a big map , had to convert towns to your cause and do some questing, defeat bunch of enemy carrying their own decks and some trying to conquer back your towns, explore various location to obtain more cards etc... to make the best possible deck you could in preparation for the final duel against an overpowered opponent.
It was a fantastic game at the time. Though it didn't managed to get me interested in the MTG card actual business, as my hobbies were very far from this kind of stuff, thankfully again for my wallet
And a few years ago, i found some discussion about how Microprose during their time had made
so many good games before their unfortunate demise, and there were people mentionning their Magic the Gathering (and the expansion i never played with) and pointed that there were people that were modding it to include much more content.
Following links i discovered there were 2 projects : Manalink and Shandalar, Manalink was the dueling engine that was part of the original game and Shandalar was a reactualisation of the actual adventure game.
Found this rather interesting to see some people were still keeping this good game alive with their work despite all those years.
But on the same place i discovered there were fan-made programs that allowed to play the actual MTG card battle, though i didn't cared much about those cockatrice, MWS or xmage as i am not an online playing guy, there were 2 other programs that kept my attention as those weren't player vs player or online based, but focused entirely into player vs AI.
The names were Forge and Magarena, that after playing with them a bit found that both were truly great.
And they're still being developped nowadays, i'm not linking as i'm unsure if this would be allowed by the Bay12 board rules, but you can easily google and find them if interested, they're really impressive piece of work and very well worth for people wanting to try without having to deal with other people or even for those testing their decks before going into competitions and stuff.
There's even a website named "Project Firemind" (again easy to google) that is using the AI from Magarena and allow people to have their deck played in AI vs AI.