Magic: the Gathering 2010 Worlds

[Primarch]

Your cards havent changed unless someone deleted the text and rewrote it. New cards have new abilities, that is true, because otherwise the game would be very short lived, but all the basic rules. Play land, tap for mana, summon monster, cast spell etc are all the same and have NEVER been changed.
You will have difficulty with things like haste and all the other new rules, but the old 1 turn win trick that could be pulled off with the original (ie black bordered basic set) cards is still possible.

[Admiral-Badruck]

Trust me somethings have changed in the order and ways cards are played... I am no sure what they are but I even pulled out my rule book and MIJ pulled his out and we found there were some stark differences.. I could not be bothered to learn a new style of play for a game I never like as much as 40k and spent twice the money on... so for me it is bye bye magic... BTW it anyone wants some old cards I have a few hundred. I am tempted to try and sell them at the card shop down the street...

[me_in_japan]

as I understand it, the rules governing the basic game mechanics havent changed. There are a bajillion new cards and thus new combos out there, but the deck that you built 15 odd years ago should still work fine. The only difference would be that your opponent's deck will be doing all kinds of mad stuff, leaving you going "huh? the whatsits doing what? with my who? eh? how can I be dead, i havent had a turn yet" and stuff like that.

[Admiral-Badruck]

and then there is that...

[Grim Ironjaw]

A select few cards have changed in function, but most still work the same as they did, just with more glamourous keywords.

The phases of the turn have changed -- you get two main phases, one before, and one after you attack.

You can mulligan a bad draw.

They recently changed the damage on the stack rule.

Most of the rest should be close to how you remember, Badruck.