The opening trainer
Your opponent doesn't play the theory. Punish them anyway.
Below 1800, almost nobody follows the book past move five. Learn your opening one variation at a time, then drill the deviations players at your level actually play, mined from real games, and every refutation checked by an engine.
Learn
One path per opening
A course is a path of variations. Each node runs three ways: watch it played and explained, play it yourself, then answer a position from the middle of it with no moves shown.
Punish
The mistakes that actually happen
For every position in your repertoire we know what players at your rating really play. The frequent, refutable ones become puzzles, with the frequency printed on them.
Remember
Reviews by position
A review card is one position, not a whole variation. A position taught in three lines is reviewed once, no avalanche, no re-drilling what you already know.
Start with an opening
As White
The Italian Game
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5
A calm 1.e4 setup: bishop to c4, c3, d3, castle, and one simple idea against everything Black tries.
As White
The Alapin Sicilian
1.e4 c5 2.c3 d5 3.exd5 Qxd5
Skip twenty years of Sicilian theory with 2.c3, then build a big centre with d4.
As White
Beat the French
1.e4 e6 2.d4 d5 3.exd5 exd5
Open the French up with the Exchange, and leave Black's locked-centre plans with nothing to lock.
As White
Beat the Caro-Kann
1.e4 c6 2.d4 d5 3.exd5 cxd5
Trade on d5, aim the pieces at the kingside, and make the solid Caro-Kann prove it has a plan.
As White
Beat the Scandinavian
1.e4 d5 2.exd5 Qxd5 3.Nc3 Qa5
Black's queen comes out on move two. Chase her with tempo and enjoy a free lead in development.
As White
Beat the Pirc and Modern
1.e4 d6 2.d4 Nf6 3.Nc3
Black hands you the centre. Take it, develop normally, castle, and no pawn storm required.
As White
Beat the Alekhine
1.e4 Nf6 2.e5 Nd5 3.d4 d6
Black's knight invites you to chase it. Accept, build the centre, and stop before you overdo it.
As White
The London System
1.d4 d5 2.Bf4 Nf6 3.e3 e6
One setup for every occasion: d4, Bf4, e3, Nf3. The opening that lets you stop worrying about opening theory.
As Black
The Caro-Kann
1.e4 c6 2.d4 d5 3.Nc3 dxe4
A solid answer to 1.e4 that gets the good bishop out before closing the door behind it.
As Black
The Slav Defense
1.d4 d5 2.c4 c6 3.Nf3 Nf6
Answer the Queen's Gambit with ...c6: the d5 pawn stays, the bishop gets out, and the plan barely changes.
As Black
Beat the London and Quiet Systems
1.d4 d5 2.Bf4 Nf6 3.e3 c5
White wants a quiet game. Hit d4 with ...c5, line up ...Qb6 on b2, and make it less quiet.
As Black
Beat the English
1.c4 c6 2.Nf3 d5 3.e3 Nf6
Meet 1.c4 with the same ...c6 and ...d5 you already know, and learn almost nothing new.
As Black
Beat the Reti
1.Nf3 d5 2.c4 c6 3.e3 Nf6
White attacks the centre from the side. Keep a solid chain and get the light bishop out in time.
As Black
Beat the Bird, 1.g3 and Larsen
1.f4 d5 2.Nf3 Nf6 3.e3 g6
Bird, 1.g3, Larsen: odd first moves, one calm reply. Take the centre and let them explain themselves.