I used to be able to play for as long as I wanted back in the day on Earthshaker and on Swords of Fury. Swords has an easy table special, and Earthshaker will light special on the outlanes twice in addition to the credit for replay. I've ran both up to the 10 credit maximum before. A good game of Earthshaker for me was around 40M, which took about 40 minutes to get.