Go is ancient strategy game with simple rules. Best way to learn go is thru game of capture-go.
Hactar Lite can play capture-go with you. Hactar Lite also lets you try go at beginner level in 9x9 board.
You can subscribe to engines playing at 5 kyu or 3 dan level.
Hactar contains over 410 go problems (tsumego). You can also add your own collections easily, or download additional 400 problem with few clicks.