There are a lot of things you can do. There are plenty of games that work well one-on-one but it really depends on what you want to do or what you want to work on.
Spelling?
Set phrases?
Target sentences?
Vocabulary?
For spelling, I like to stat with jumbles or visualized spelling (spelling and reading the word outloud without writing) and reading. You can also teach some phonics and read some simple sentences together.
For set phrases and conversational items, you need some activities or role plays. I like to construct things like a town to practice 'It goes here.' Or pretend to make dinner and sit down with some flashcards to eat. 'Could you pass me the ~?'
Target sentences -
Bombs Away,
Othello/Reversi,
Jenga, concentration ... You just need to work the target language in to some existing game or make a variation of you own. It's best if the language is secondary to the game (English ability doesn't give you an advantage) since you'll be playing as well. It's even better if winning/losing is more a matter of luck.
I hope that gives you a little to work with.