GridMaster provides a graphical user interface and artificial opponents for the game of Go (Igo, Baduk, Weiqi). It contains a full featured SGF reader/editor, a lite version of the 9x9 Olympic Champion Go program Steenvreter (it also plays larger boards), and a Go Text Protocol (GTP) interface to connect other gtp-compatible engine (more opponents can be downloaded/added). It can be used as a tool to play, study Joseki, solve Go problems, make diagrams, annotate games, etc.

If you are new to the game of Go, an introduction as well as some links to more information is included in the help (only available in English).

Here's a non-exhaustive list of features:
- Full featured SGF reader/editor (perhaps the only Android app to support all properties in SGF4)
- Includes a fairly strong artificial opponent (Steenvreter lite, level configurable, support for ARM and Intel cpu's)
- Ability to add other bots such as Leela Zero, GnuGo, Pachi, or your own GTP engine (for help installing Leela Zero see http://gridmaster.tengen.nl/howto/add_leela_zero.html)
- Tool for reviewing games (easy to rate moves/states, add comments, links, game info, etc.)
- Setup *any* position (including illegal ones, e.g., for demonstration purposes)
- Quickly opens large SGF files such as Kogo's Joseki Dictionary
- Supports all rectangular board sizes up to 52x52
- Tips at start-up (can be turned off)
- Accurate stone placement even on small screens (several input modes available)
- Correct wrong input by shifting stones
- Zoom in to show only some part of the board (by pinching)
- Zoom out to show the game tree
- Fast navigation through the game tree (button push + slide action)
- Auto-replay games at configurable rate (long-click forward to start).
- Collection support (i.e., multiple game trees in one file)
- Share option
- Export to image file
- Copy-paste variations/games (also between applications as sgf text)
- Configurable rules (Chinese / Japanese)
- Configurable time (Absolute / Canadian / Japanese / Stopwatch)
- Configurable sound for stone placement & clock
- Various graphics options (configurable in settings)
- Full screen portrait & landscape modes
- Indicate last and/or next move
- Extensive help, includes an introduction to Go (only available in English)
- Optional debug tab shows GTP streams (the communication between GUI and engine), rules issues, and provides option to send gtp commands manually (double-tap or long-press to pop up dialogs).

An ad-free version of GridMaster is available at:
https://play.google.com/store/apps/details?id=nl.tengen.gridmaster.go

If something doesn't work, send me an email. Suggestions for improvement are always welcome. Also, any help with translations would be greatly appreciated!


P.S. Some crooks are actively manipulating the ratings, and Google provides no means for lone developers like me to fight it. Sure I could join the war, buy fake likes, drop fake 1-star reviews on competitors, waste money on ad campaigns, etc., but this is just a hobby for me and it should remain fun! So far all growth has been organic, and I'd really like to see it continue that way. So, please be nice. If you have tried the app and like it, please give back a little and rate it 5 stars! I understand some of you may want to be more nuanced, and I do also appreciate 4-star ratings, but please notice that they don't help much; the bad guys give very low ratings, and currently even 4 stars pull the rank down, so the only real help comes from 5-star ratings and sensible review comments.