I create games like Deluxe Pacman because it is really fun to create a good looking game and know that people around the world are enjoying themselves as a result of my work. It is also fun to mess around with graphics, sound effects etc... and to give back to the freeware-community something.
And, of course, its nice to see all the positive (and some negative) feedback about my creations. And, for example to see Deluxe Pacman at Game Hippo's number 1 in the popular download section twice, makes me a little bit proud.
On the other hand it's sometimes just (hard and boring) work. There is a gap between having a nice idea and testing out that it works and providing a end-user compatible working solution, test it on different operating systems, keep it updated and fixing all the major and minor things that went wrong.
And providing all the writings and web pages. Quickly answering emails, too.
So a donation keeps my moral high, my fridge stocked with diet cola and Deluxe Pacman (and other titles) running in the future.