You can register an account to play Eternal on Dire Wolf Digital's website: https://www.direwolfdigital.com/eternal/. After creating an account, there will be links to various ways to play the game (PC/Steam, Xbox, iPhone, etc.).
[Editor's note: If you want free stuff, you need to use someone's referral code link to register. If you don't know anyone yet, head over to reddit's Refer a Friend Thread and grab one. At present, a new player receives free Servants of the Spire deck upon completion of the tutorial.]
Game Tutorial, and how to skip it
Once you start the game and log in, you'll be put directly into a game. This is the first of about 16 games in the tutorial that teach the basics of Eternal. There are also some light story elements, but you can skip the rest of the tutorial at any time by going to the menu (gear icon in the upper right) and selecting Account then Skip Tutorial. You can always go back and play any tutorial levels later. Every three tutorial games after the first awards you a preconstructed deck (precon), but skipping the tutorial awards them all instantly.
At the end of the tutorial (finished or skipped), you'll also get three silver chests. Chests have about a 10% chance to upgrade to the next highest rarity, so you may luck into a gold or two. Worst-case, the three chests award about 750g and three uncommon cards.
You'll get a prompt about your play style. Your response doesn't matter, but it's worth 500g, so there's that.
Building Your Own Deck
For now, hop into the deck builder by clicking the Cards button near the top, then the New Deck button on the left. The free cards from the precons are all available to use, as well as the three uncommons from the silver chests. Getting used to the interface for putting together a deck takes a little time, but I'd recommend putting together:
This starter deck has some aggressive units to play early and deal some damage to the opponent, then some bigger units with good effects or flying. It was good enough to get me through a beginner Gauntlet run, but one of the preconstructed decks would also probably work just fine.
Farming AI Game Modes
Speaking of Gauntlet, that's the next destination. Play until you get to the boss at the end and win. If you went with the starter list above, you should pick up enough Justice and Fire experience to get to level 3 with each (these faction levels are mostly for vanity, but offer small rewards). Level 2 gives 100g each and level 3 gives 100 shiftstone. Defeating the Gauntlet boss for your 7th win in the run awards a free Forge ticket, two silver chests, a rankup chest (about 250g and a pack), and your first two-faction preconstructed deck.
Now is a good time to verify your email, and there's probably a pop-up on the main page bugging you about it. This nets 3 packs of The Empty Throne, which doesn't hurt. This was the first set released for the game, and has some good cards. Assuming no chest upgrades, that's about 2,200g, four packs, and 200 shiftstone in rewards thus far.
That free Forge ticket waives the normal 2,500g entry to Forge, so that's up next. Forge is one of the three limited formats in Eternal, meaning that the card pool you use to build a deck is limited by your choices in the event (a limited card pool). The other two, draft and league, are played against other players. Forge sees you pick 25 cards in 2 factions to build a 40-card deck to play against the AI (you keep the cards). The other 15 cards are an auto-generated power base, so choose cards that help you find power or influence accordingly.
Playing through Forge should get you the reward of 2 silver chests plus the results of your run. With 7 wins, that's 2 gold chests and 1 rank up chest (about 2,000g and 4 packs). That Forge run should unlock draft with just enough gold for one admission. If not, another go at Gauntlet should do it.
I recommend most players prioritize picking rares (blue pip at the bottom of the card) and legendaries (gold diamond) in their first couple drafts to turn into shiftstone for crafting their first constructed deck. [Editor's note: Choosing the cards with the highest value in raw materials is often referred to as"rare drafting".] Making a functional deck out of your picks can also net some extra value out of your winnings, and it doesn't hurt to play the games. You can end your run between games by going to the menu (gear icon in the upper right) and clicking "Resign Event".
After drafting, you can destroy the cards you don't want for shiftstone. The conversion rate is decent, with a rare giving enough shiftstone (200) for 4 commons or 2 uncommons. Rares themselves cost 800 and legendaries 3200, meaning destroying a legendary gives enough shiftstone for a rare of your choice. Promo cards cost 600 shiftstone, but there are only a few that I'd recommend crafting before rares, depending on the deck. Right clicking a card in the Collection screen (from the Cards button up top) lets you either destroy a card for 1/4 its value in shiftstone or craft another if you don't already have 4.