I also like how these are actual playing cards and you can really play a game with them. We didn't want anything that was long winded and took a lot of attention, so we decided to play 'snap' after we indulged in some massage and foreplay.
Once we were suitably warmed up, we dished out the cards and played. Whoever won the 'snap' got the choose which of the two positions on the corresponding cards we would do. We set a timer for two minutes and after two minutes we had to stop and go back to the cards and play again.
It sounds quite frustrating having to stop having sex to play, but it was so much fun having that frustrating building up inside of you and quickly trying to get to the next position. There's a very good amount of positions that we hadn't tried, which I thought was great, but it certainly gets you more and more aroused getting used to the new sensations in different positions.
Looking forward to reading what other ideas people have had!