They actually make a VIDEO game of the magic cards now. You can get it on PS3, XBox, IPad, Steam.
So you can play a virtual version of made up playing cards. (!)
It's terrible.
There is, however, Magic Online that is exactly cards in real life. You buy packs, trade, sell, build decks, and they have tournaments for cards/packs/money. It is just as expensive as playing in real life only you get absolutely nothing real for it.
I take that back... if you get an entire set of one expansion in Magic Online, you can trade it for a real one.
It's a dorky money-pit if you're playing to be competitive. So unless you have tons of money and tons of time, have fun with the pre-mades at work.