ConnectFour Studio

ConnectFour Studio is a free, offline Connect Four program: play against the computer, analyse positions and run engine-versus-engine matches. It is the Android version of the desktop program of the same name, with the same engine, levels, help and texts.

Engine

Perfect play: a Kotlin port of the BitBully solver by Markus Thill (bitboards, MTD(f), transposition table) with the 12-ply opening book with distances – identical results to the original C++ engine

15 levels: 0 Loser (joke level), 1 Random … 14 Perfect, defined by (p, s, w): share of perfect moves, loss guard and win guard

Two custom levels User (1) and User (2) with your own (p, s, w)

Analysis

Evaluation row under the board: win / draw / loss for every column and the number of stones until the end

Permanent analysis after every move, one-off evaluation of all moves

Info box with depth, value, nodes, time, speed and source (book or computed)

Game modes

Human vs. computer (the computer can also open), two players, computer plays out the position

Computer-computer match with up to 10,000 games, colour swap, three speeds, Elo difference and copyable result

Session score human vs. computer per level with Elo estimate

Random start positions with 1–9 stones and a chosen result

More

20 boards with matching stones, ghost stone, drop animation, last move and winning line marked

Load and save positions as .4gp files (compatible with the desktop version), quick save

Detailed help with search and zoom, user interface in English, German, French, Spanish, Dutch and Italian

Portrait and landscape, phones and tablets, keyboard shortcuts with a hardware keyboard

No permissions, no internet access, no ads, no tracking

License: GNU AGPL v3. Engine: BitBully by Markus Thill (AGPL v3), opening book: bitbully-databases (MIT).