GridMaster provides a graphical user interface and artificial opponents for the game of Go (Igo, Baduk, Weiqi). This is the pro version (ad-free). 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 (so more opponents can be 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 (but 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, supports 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
- 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 timing (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
- 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).

Before buying, try out the free version of GridMaster (https://play.google.com/store/apps/details?id=nl.tengen.gridmaster) which is currently identical except for the ads.

If something doesn't work, send me an email. Suggestions for improvement are always welcome.