Tactics Ladder

Tactics Ladder is an offline chess tactics trainer. The puzzles, the rules
engine and every word of text ship inside the app: no ads, no network, no
account, and nothing to buy. Every theme, every level and every explanation is
open from the first launch.

720 PUZZLES, ONE SOLUTION EACH
Twelve themes of sixty puzzles, and inside each theme five levels of twelve.
Before a position enters the app, the engine scores every legal first move and
proves that no second move does the same job, that the line is forced and that
the defence has no escape outside it. A puzzle with two answers never ships.

THE POSITIONS ARE OURS
Every position was generated and checked by the app's own rules engine. No
puzzle collection, no book and no third-party database was used, and the hints
and the explanations are written from the position itself.

TWELVE THEMES
Fork, pin, skewer, discovered attack, double check, windmill, back rank,
deflection, decoy, trapped piece, mate in two and mate in three. Each theme
says in one line what the motif is, and a level opens as soon as nine of its
twelve puzzles are solved.

THE FULL RULES OF CHESS
Castling with every square checked, capture en passant, promotion to a queen,
rook, bishop or knight, checkmate, stalemate, the fifty-move rule, threefold
repetition and insufficient material. A move that would leave your own king in
check does not exist, so you cannot play it by accident.

HINTS IN THREE STEPS
The motif, then the piece that solves it, then the square it starts from. Take
one step or all three, as often as you like: there is no daily limit on hints.

THE WHOLE LINE, EXPLAINED
Step through the solution with the arrow buttons and read what each half-move
does. After a solved puzzle the full breakdown explains every half-move of the
line and why two tempting moves fail.

EVERY MISS COMES BACK
A puzzle you miss returns after one day, then three, seven, sixteen and
thirty-five. Solve it cleanly and the interval grows a step; miss it again, or
open the solution, and it goes back to one day. Two clean solutions at the long
intervals close it for good.

STATISTICS
Solved and attempted, accuracy on the first try, the share solved without a
hint, wrong moves, average time per level, your longest and shortest puzzle,
the day streak, the review queue, where the misses are by theme and ninety days
of activity. Progress can be written to a text file on the phone.

MADE FOR ONE HAND
Tap a piece to see where it can go, then tap the square; dragging works too.
Flip the board, turn coordinates on or off, pick a board colour and a piece
set, and choose a light or dark theme.

NOTHING IS TAKEN AWAY
Solved puzzles, the review queue and the statistics stay as they are. There is
no in-game currency, no points to spend, no lives, no energy and nothing to win
or risk.

OFFLINE AND PRIVATE
The app has no network code at all. Nothing is collected, nothing is sent
anywhere, no advertising identifier is read, and it asks for no permissions: no
camera, no microphone, no location, no contacts, no notifications.

Recent changes:
First release.