I found Earthshaker at the arcade with what appeared to be 2 credits on it. I played a game. Still 2 credits. Well that's odd. I played another game. The number of credits still didn't change! I eventually played 2 or 3 more games and the credits counted down as they should. A weird software bug? A hardware fluke in the CPU? I'll never know.
I don't like it when a game is set to 3 plays for $1 and you don't realize this until you put 4 quarters in. For example: put in the first quarter, see half a credit on the display. Put in another, see 1. Another, see 1 1/2. Put in the 4th quarter, you see 3. I prefer to see 1: 1/2, 2: 1, 3: 2, 4: 3. This way I actually know that the game is 3 plays for $1 instead of 2. Otherwise I might not have put 4 quarters in to begin with and instead I may have spent that money on a game I know for sure is 3 plays for $1.
Here's something interesting. At 3 plays per dollar you spend about 33¢ per game. At 33¢ per game you spend about 3.6¢ per ball. Not bad. But at 2 plays per dollar you spend 50¢ per game and 5.5¢ per ball. Likewise, for 75¢ per game you spend 25¢ per ball and at $1 per game you spend 33¢ per ball. Plus, you'll be spending a whole (insert game price here) on just a single ball if you buy in. Ridiculous!