Caissa Codex
A40

Colle System: Siroccopteryx Variation trainer

Back to the opening, all openings to practise or my repertoire

Type a move and press Enter: e4, Nf3, O-O, or from and to squares like g1f3 (e7e8q to promote). The board is also played with the mouse.

Practise the Colle System: Siroccopteryx Variation

Play Black's moves of the line from memory — 1. d4 g6 2. Nf3 Bg7 3. e3 c5 4. Bd3 cxd4 5. Nxd4 Qa5+ — and the trainer plays White's replies; "Play the other side" turns it around.

Read about the line, its statistics on Lichess and Stockfish's evaluation on the Colle System: Siroccopteryx Variation page, or pick another opening in the opening trainer.

https://chesscodex.org/train/colle-system-siroccopteryx-variation