Here's an interesting game for (at least) 2 people that can really get the ball rolling about what makes strategy. All you need is a deck of playing cards.
Rules Give each player a suit. This is their hand- they see all of it at once. Each player selects a card and places it face down on the table. When all players have placed a card, flip the cards up. The highest card wins (you can choose if aces are high or low- it makes no difference). The winner of a round takes the cards from that round and puts them in a score pile. In the event of a tie, set aside this round and the winner of the next round takes it. When all cards have been played, the winner of the most rounds wins.
Questions This sounds so simple you're probably think it's a baby game for silly babies. Well, maybe so, but here are some questions that should get you thinking. 1) What is the best card to open with? 2) What is the best card to respond with? 3) What card (if any) should you be reticent to play? 4) Is there a strategy that you could have a computer use to win this game every time it played?
If people like this, I'll post more thought experiments about strategy and game design. Even if people don't I will! In the meantime, enjoy this simple game for 2 players!