We've did some pretty long flights with our kids when they were babies - the longest was 21 hours with a 3 month old and 23 month old - and yes, it was long! As you've flown before I'm sure you are aware that the biggest deal will probably be ear issues. I absolutely loved it when we bought a carseat/stroller that was approved for some airlines. (Always check this - but when it worked, it was worth it's weight in gold!)
Regarding games etc. I think the best thing is a bunch of different items that you can bring out as 'new' as the journey progresses. I'm not usually one for dollar stores, but buying cheap puzzles, books etc, which won't be a great loss if they're ruined or lost, helped a lot. Good luck.
