Welcome to Scratch Chess - "Game of Kings". FAQs: - "Why invalid move?" Quite likely your move puts or keeps you in check. - "Castling doesn't work!" It does, see castling rules. - "Too difficult!" Switch to junior mode (press 'j'). - "Too easy!" Play on Forkphorus (link below), use fast system. - "I found a bug!" Please describe in detail and copy&paste 'Moves' PGN data or 'Export' PEN data. - "Opponent pawn captured my pawn which had already passed it!" That's called 'en-passant'. - "How to castle?" Move the king two squares; none of the passed squares must be in check, and neither king nor rook must have been moved before. - "How to play en-passant?" Move your pawn diagonally by one square, behind the opponent pawn which just moved two squares. - "Can you increase the engine's playing strength?" It has been tuned a lot already, and we probably reached the end of the rope now. A Scratch chess engine will never play at the level of one implemented in C or C++. Scratch is slow due its interpreted nature, every variable access triggers a table-lookup by name, it doesn't have bitwise operations for bitboards, and uses variants with constant value conversions, etc. - Easy: 5 seconds think time (Junior: 0 seconds) - Medium: 15 seconds think time (Junior: 0 seconds) - Difficult: 30/20 seconds midgame/endgame think time (Junior: 1 second) Press 'c' to toggle 60 seconds think time on Difficult Press 'd' for iterative deepening debug info Press 'p' for profiler mode (Scratch 3.0 and Sulfurous only, as Scratch 2.0 lacks hi-res timers) BUG REPORTS: Please describe exactly what happened, and if possible provide exported board data: Click "Export", then look for the FEN data, select the text by triple-clicking it, copy it to the clipboard and paste it to the bug comment. Alternatively you can also export the move list in PGN format (click "Moves"). Please also report the difficulty level, and whether you are playing in junior mode. Before you post a bug, go sure it really is a bug and not a misunderstanding, e.g. you may want to consult an experienced chess player beforehand. Thank you! I focused on playing strength and usability. Considering the speed limitations of Scratch it shouldn't be too bad (it usually calculates 4 to 8 moves in advance (max. is 20 moves), depending on selected level, board complexity and system speed). Looking forward to feedback in the comments!
