This is a card solitaire game in which matching cards allows your offense or defense to do their job in the game. Match enough and you'll have the forward motion you need for a first down on offense. On defense, you'll stop the opposing player's advance.
Having to draw a card carries the possibility of a "Big Play", a short text event that can end the play or change it significantly. And it might not end in your favor! Your draws are unlimited on offense, with a high possibility of a Big Play, but on defense you have a limited number, with a lower possibility of the play ending suddenly. This makes for an interesting dynamic, with poor play leading to even good defenses collapsing. The mechanic forces you to allow your opponent some gains, and hopefully you can hold them to less than they need for a first down without drawing.
Another mechanic has you attempting to guess your opponent's play call (run or pass, it's not complicated) before each play. Each team has stats for running, passing, special teams and the like, so you can predict somewhat how they will play. If you guess correctly, you get an extra card slot for the play, which is a big advantage.
Teams are tracked through a season and rated relative to each other. Don't pick a weak team hoping to play it up, at least not to start with. That's a sure path to disappointment.
There are three difficulty levels, which affect the basic yard totals for plays based on your play guessing, and this is a solitaire game, so no multiplayer.
The football mechanics are notional - you need forty yards to complete a first down. Why? Because this helps shorten the game so that a hand of solitaire is not an hour long. :-) There are still halves and quarters, and punts and field goal attempts.
This is a fun game of football and cards, enjoyable whether you understand football or not. Buy it! You'll like it.