A misunderstood game of the 80s generation. People either loved it or hated it. My whole family loved it. I remember playing for about 4 hours straight on one quarter at age 7. It's quite a feat in programming if you think about it. According to folklore and rumours on the internets, it was written over a weekend and basically "shipped" soon after. I think there are 3 different ROM versions but overall there were very few bugs in the game.
I've crashed it many times with the 'snow death' crash by shooting in the upper left hand corner just right and of course there is the Brains bug that gets them stuck in the corner, but the sheer playability factor of the game still holds up today. It is great for hands/eye coordination training.
A lot of games today have lots of lush content and amazing graphics, but the replay value doesn't hold up. Back then, you had a few pixels and colors to paint your landscape, so you had better make it fun somehow, otherwise it would end up in the backroom next to Spy Hunter 2 and other forgettable arcades.
That said, I think I'm going to go play a few rounds.
[edit: After playing a while, I found a really good paragraph from Eugene Jarvis that supports what I said above, ironically]
For me the retrogaming movement is more than just nostalgia of misty eyed Gen X'ers. It's a reaction to the current graphical overkill, the simulation obsessed gaming environment of the late 90s. In our quest for absolute graphical realism, we have forgotten the basics of gaming. Look at "Virtua Fighter 3" vs. "Virtua Fighter 2." Unless you are a proctologist, you can't find a dimes' worth of difference in the gameplay. It is clear that the design team focused on the beautiful water effects, facial expressions, awesome backdrops, and 400 polygon, fully rendered loin-cloth animations. Have we as game designers become mere interior decorators, spending months on the reflection mapping of candlelight, or loin-cloth motion capture? Have we forgotten the essence of gaming which is to present the player with novel and original challenges? Once you've seen the interior decoration, there's no need to come back. You need a game in there.