So, I've got a few more ideas for iPhone games (stuff that is within the realms of possibility for me to write on my own

)
One of them is the sort of game that has potential to be a randomly continuing game until there are no more possiblities type of game. But at the same time it has potential for a series of pre-written puzzles.
I haven't actually written anything for the games yet but was wondering if anyone has any experience of making puzzles in the past? Whether doodling on paper at school or writing them on a computer etc...
This particular one I'm thinking of is a grid based game if that helps.
Not much to go on I know but it would be nice to have someone to discuss ideas with.