Kropki

Kropki (or "Dots" in English) is a paper and pencil game very popular play-during-lessons-in-school game. It seems this game was invented to play Go with paper and pencil - in contrast to Go you can surround empty spaces together with opponents dots, and the surrounded areas are off limits for the rest of the game. Go experience is helpful, but many tactics work differently.

There are Wikipedia articles in Polish and Russian and Czech.

You can also play online.

Here is an online interactive tutorial with problems to solve:
http://www.tochki.org/lesson/eng/index.html