Some games I just can't make hard enough so I sold them.
Having a hard game to play is very important to a home collector as we play a lot and they become easy really fast.

For example my MM was way too easy. The 2nd game I played on it I blew up all 5 castles. Thats the main feature of the game and I completed it after the 2nd game.
I know there is much more to the game than the Castle but come on this is the main feature of the game!!!! What else is there besides hitting the two ramps over and over and over. I couldn't make it harder as to do that would mean I would have to increase how many times I hit the castle door and it was already way too much. I didn't want to play a game that consisted of just bashing the castle door, which by the way is an extremely easy shot, over and over and over.
I tried to make the game more appealing, especially after the $$ I spent to get it, but there was nothing I could do but sell it.....and that was easy too.
IMHO that game has a big big flaw....it was too dam easy to complete the main feature of the game and the other things the game has to complete it just wasn't doing it for me.

Now AFM is essetially the same game but because the Mothership is difficult enough, it's not easy to blow up all the ships, it makes the game the best one I've ever played. Difficulty can make or break a game IMO and sometimes opening the outlanes and making it steeper just isn't enough.