Ghostbusters for the Master System is a strange game. It just throws you in and doesn't really tell you what to do. You start with an overview of a city in which you control a Ghostbusters-logo driving through the streets. Quickly, you'll figure out you have to enter the blinking buildings as quick as you can to catch the ghosts that are in. The "buildings" act as residential areas as well, forcing players to, yet again, drive to the address and bust some ghosts. Though simplistic, I actually enjoyed racing around and catching those ghosts.
By catching ghosts you earn money that you can use to buy some useful power-ups that make the game a lot easier. You have to catch a certain amount of ghosts before Marshmallow Man turns up and starts destroying the city. However, it was never fully clear how many ghosts you need to trigger this monumental event. Fail to catch enough ghosts and it's game over, which means starting the whole process over again.
If you succeed, then you're ready to enter the second part of the game. First, you have to enter a building in front of the Marshmallow Man. You get three tries to do this, which certainly adds pressure to the situation. If you manage to get in, you go upstairs in a platform-like section shooting ghosts and in the end you face Zuul.
The graphics of Ghostbusters are decent. Although it has been released on plenty of other consoles (including the NES, Commodore 64, MSX, Atari 2600 and multiple other platforms), this Master System port is the best looking. The sound is decent as well. It's especially good if you like the Ghostbusters-tune in MIDI-format, since that is what you'll hear all game long.
Overall, I enjoyed Ghostbusters. The initial goals are a little vague, and the gameplay probably doesn't suit anyone, but I'd still recommend you give the game a try. Just don't cross the streams!