I want you guys to have the best experience possible, so here are a few things to keep in mind during your first hour of play.
First, pay attention to the tutorial. It only lasts about 10 minutes, but it explains everything you need to know in terms of the rules. The rules aren't complicated, but you do need to understand them.
Actually, what am I saying? Nobody pays attention to the tutorial. Okay, let's start from scratch here.
There are two major areas of gameplay in GS: strategic decisions related to football, and strategic decisions related to the tableau (the cards in front of you). The football decisions are the same that a football coach would make during a game: run/pass playcall, down and distance decisions, when to kick, time management, etc. That's basic football, so no discussion needed (I'll put up a separate guide for those of you who are unfamiliar with American football).
So let's talk about the tableau.
The basics:
--playing cards either increases your gain on offense, or reduces the opponent's gain on defense.
--valid "matches" are cards within 1 rank and opposite color (so red 2 and black 3 would be a valid match, for example).
--1 and 13 are NOT a valid match. This is important to the card gameplay and will be discussed shortly.
--on offense, if you run out of valid card matches, you can press the "Big Play" button. When you press the Big Play button, you will either get another card or trigger a text event, which could have a positive or negative outcome. In gameplay terms, this represents risk.
--on defense, you receive an allocation of Big Play presses per half. They're much less risky in outcome terms (a negative event when you press the Big Play button on defense is very rare), but the risk lies in their limited supply. So you need to decide when getting an extra card (which will possibly result in more matches to reduce the opponent's gain on the play) is important.
The card play may seem simplistic at first, and you can certainly play it that way, but because 1-13 is not a match, certain cards are better to have on the tableau than others (with three specific levels of quality). I'm not going to spell that out for you, because I want you to discover it for yourselves, but good card play is a continual process of replacing "bad" cards on the tableau with "good" cards as soon as possible. This affects what order you'll play your matches, if you have more than one showing, and what you want to match the wild card with (wild cards show up occasionally and can be matched with any card).
On Rookie difficulty, you will quickly be able to win. Rookie is really only for people who have no understanding of American football and my Mom (love you, Mom!). The AI is very, very simple on Rookie.
As soon as you move up to Veteran level, though, the AI is very strong. The decisions you have to make on every play are much more consequential, and the game becomes very challenging. So as soon as you feel comfortable on Rookie, move up to Veteran. You can change the difficulty level during a season in the Options menu, so you can move back and forth at will.
Also, don't worry about losing. That's part of every season (some more than others). No matter how strong your team is, you're going to lose games during a season. The game is not about being perfect, it's about adapting to changing game situations and making sound decisions.
That's enough for now. I am happy to answer any questions you have via e-mail or in the Steam forums, and I'll compile a list of the most frequently asked questions and post it in a few days.
Oh, one more note: if you use a pen tablet for your input device, GS should work fine with it (that's what I use), and you can select cards very, very quickly that way. Also, if you have Windows 8 and a touchscreen-enabled device, GS works fine with those, too. You'll just need to use a regular keyboard for editing teams, but other than that, you're good to go with touch. I test on Eli's ultrabook all the time.