I don’t know the game, but skimming
https://media.wizards.com/2019/downloads/MagicCompRules%2020... (not the best organized of texts, IMO. ‘Normal’ game rules start describing the goal of the game (
https://www.fide.com/component/handbook/?id=171&view=article:
”1.1 The game of chess is played between two opponents who move their pieces on a square board called a ‘chessboard’. The player with the light-coloured pieces (White) makes the first move, then the players move alternately, with the player with the dark-coloured pieces (Black) making the next move. A player is said to ‘have the move’ when his opponent’s move has been ‘made’.”
Similarly, the rules for bridge (http://www.worldbridge.org/wp-content/uploads/2017/03/2017La...) start
”Duplicate Bridge is played with a pack of 52 cards, consisting of 13 cards in each of four suits. The suits rank downward in the order spades (), hearts (), diamonds (), clubs (). The Cards of each suit rank downward in the order Ace, King, Queen, Jack, 10, 9, 8, 7, 6, 5, 4, 3, 2”
As another example, couldn’t those “in a Emperor/Commander/multiplayer game,…” sections be grouped by type of game?), there are decks, stacks, sideboards, zones, one of which is the battlefields, and libraries. Presumably, they all behave differently.
If those aliens don’t know what these words mean in this world, are they going to figure out what they mean in the game from reading the cards? For example, rule 405.2 ”The stack keeps track of the order that spells and/or abilities were added to it. Each time an object is put on the stack, it’s put on top of all objects already there.” isn’t hard to infer if you know what a stack is, but if you don’t?
Similarly, I read ”An effect may state that a player wins the game.”. Chances are those aliens will think that’s the only way to win.
Also, that text is full of extremely weird rules (“A card’s name is always considered to be the English version of its name, regardless of printed language”) that, I guess, are impossible to discover from the cards only.