Now, let's look at who published both games, Wizards of the Coast. WoC makes many card / strategy games (such as Dungeons and Dragons, and Pokemon TCG), and also happened to make Magic, and Yu Gi Oh. Now, Magic was released in 1993 by WoC and features the player hoarding mana to cast spells and release artifacts on to the battle field. Sounds simple enough, all the creatures have an attack and a defense number, and those numbers can conceivably be manipulated by other cards. Yu Gi Oh is the result of a company slimming down a lot of the strategy and making the numbers bigger.
A powerful card in Magic is an 8/8 (8 attack points, and 8 defense points) and requires quite a bit on mana (I would guess, 7 to 9). A powerful card in YGO is a 2,000/2,000 (notice the same attack/defense pattern), and requires just that it is the player's turn to lay down the card. Also, in MTG, one's life points is equal to 20 (that can be manipulated as well), and in YGO, life points are 2000. Bigger numbers doesn't a game a better.
To the point: everything done in Yu Gi Oh can be done in Magic. Magic came out first in 1993. Yu Gi Oh has a lot of things going on, and to be fair to YGO lovers, I will us the earliest release date that I can find (which isn't for the card game, it's for the original airing of the Japanese show), and that is December, 1996. I don't want to start a nerd fight, but the same company used essentially the same formula to make essentially the same game.
Now to some more opinionated stuff. the show of Yu-Gi-Oh is not well written, and is extremely cookie cutter to many Japanese copy write things, as is the manga. The story is about some kids who play a card game. In Magic the Gathering, the player is the story, when one make their own deck, one becomes the story. MTG has no corny show, no poorly written manga, and no other things going for it BUT the game.
Now how is Yu-Gi-Oh a copy of MTG? Allow me to dig further into the obvious. Magic came first, so even the show and manga of Yu-Gi-Oh could have gotten the idea from the alpha and beta Magic sets. But that doesn't hold up very well because it would then be by chance, correct? Well, now digging further, they are both made by the same company. But that also doesn't hold up, because companies can make many different things.
Past the superficial, I will be fair and construct my case on why I truly think YGO copies MTG. Here is an example of a Magic card.
Here are some facts:
1. Notice in the lower right-hand corner, two numbers. Attack and defense. One can choose to attack during an attack phase, or defend when being attacked.
2. Notice in the middle between the picture and the effect, there s a rare mark, and a creature type.
3. Notice in italics is a quote, and about that is a "flying" and some effects of the card.
4. Lastly, notice the at the top there is a number with 3 stars next to it, that's a mana cost.
Now here is an example of a Yu Gi Oh card...
Here are some facts:
1. See that in the lower right hand corner? That's an attack and defense score! Strange, that's on the Magic card too, in the same place... But surely it's used differently, right? Not quite, the player can attack during attack phase, or defend when being attacked. The attack and defense score is equivalent to a 15/10 in Magic.
2. Rare mark is where the stars above the picture are, and creature type is above the quote (recognize any similarities yet?)
3. Wow, there's a magical whimsical quote in the exact same spot as in the Magic card!
4. Now, where's the mana cost? Surely this creature can't just be layed out because it's so powerful! Oh, nope, no mana cost.
I think that's some pretty conclusive evidence... Yu-Gi-Oh is a simplified, ripped of version of Magic: The Gathering. But the same company made them, so congrats Wizards of the Coast, you made more money by making the same game.