vocabulary.co.il has a large collection of vocabulary, spelling, grammar, and also some typing games. Most of the games are divided into grades, so you can choose a level that’s appropriate for you. For EFL students, try some of the junior high level games, and if they’re too easy for you, move on to high school level or the SAT games. The SATs are similar (sort of) to the Center Test in Japan.
Here are just a few examples of the available games. There are many, many more to explore.
Homophones: this is the 6th-8th grade homophones game:
“Eight letters in search of a word”: see how many words you can make with the available letters: