If you don’t know what a battle forged army is or how stratagems work, you need to read this part first.
If you played 40k back in 7th edition or earlier, or if you hav played Warhammer Fantasy, or Age of Sigmar, the information here should be enough to get you started. (If you REALLY have no idea how these games work, start with the 40k Wikipedia page.)
Winning the Game:
There are various matched play scenarios in 40k that you might encounter in tournaments and casual games, all of which require players to score victory points by capturing and holding primary objectives. Because of this, the ability to take and hold particular points on the battlefield and defending them successfully might be as or more instrumental to winning the game than obliterating your opponent’s army. (In fact, in 9th edition you can win the game even if your opponent completely wipes out your army, although this is rare.)
Players can also score victory points by achieving secondary objectives, which are chosen by each player before the battle begins. There are many secondary objectives to choose from, some of which allow you to earn points by eliminating enemy units, but the majority are about board control in some way.
In 9th edition 40k players’ armies must must fit into formations called detachments, which have certain requirements and limitations. For example, a “battalion,” must have 2 leader models called “HQs,”( but no more than 3;) 3 troop units, (but no more than 6,) no more than 3 heavy support units and so on. Having to organize units into detachments forces players to field armies that feature a variety of units types.
Command Points and Stratagems
Each player gets a number of command points at the beginning of the game. How many command points you get is determined by the size of the game, so in a 2K match for example, each player starts with 12 command points, (although you start with fewer if you organize your units into multiple detachments.) In addition, each player generates 1 command point at the start of his or her turn. These command points are necessary in order to use stratagems, cards that provide powerful situational bonuses. Although you can play 40k casually with rudimentary knowledge of three or four stratagems, in order to play more competitively, you need to develop much more comprehensive knowledge of what you can do with your army’s unique stratagems and what your opponents can do with theirs.
Here is a stripped down version of the rules
If you want to see some game play, just good “40k Battle Report” and you will get dozens of videos- some pretty high quality- with run downs of people’s games. Otherwise, if you are ready to start thinking about building that really cool eldar army you came here to learn about, you are ready to move on to: an overview of eldar craftwrolds in 9th edition.