The games dropdown menus exist to help standardize the options available
(example: 4E vs. 4th Edition vs. D&D4). No matter how many
games are listed, some may not make the cut. Games are added to the list
periodically. This ensures obscure listings gain greater visibility
when sorted via the Other Games option and helps keep away “empty” search listings for underrepresented titles. You don't need a system to be in the dropdown
list to play it; use 'Other Games' and put the name of the system in the
listing text, all the forms of it someone might use. Actually play the
game. Ask those you know who play the game to do likewise. The Devs have stated the Suggestions
forum will never be a viable way of getting games into the dropdown
menu, so don't be surprised if/when this thread is closed to release your votes.