I just played Blaster Master with a friend over the weekend to contribute to RetroActive, my favorite feature on Nintendo World Report.
I had a used copy as a child from vacuum cleaner repair shop. For some reason they sold random electronics as well, including NES carts. I loved it because the gameplay was so varied, the tank portion, jumping out of the tank in the overworld, and the top-down dungeons. It was always very hard and I never could pass the 3rd stage because I never placed proper emphasis on the GUN powerups. I once saw my adult neighbor get the walk climbing unit, but never beat the game.
When my friend and I played it this week, we started playing normally, only intending to use save states but we quickly decided to turn on infinite hover and sub-weapons. Eventually, we just busted out the full walkthrough maps.
http://www.auriplane.net/blastermaster/01-level1-a.pngI love this game still, despite the fact it doesn't really respect the players time. My friend's first console was the SNES, so he doesn't really see what all the fuss is about. It really is one of the best games on the NES, easily top 25. 10/10 ambition, 7.5/10 for execution. Limited continues is just cruel.
I'm bought Blaster Master: Enemy Below in high school, but never finished it. Now that it's on 3DS I'm planning to go back and finish it.
If you liked this game, you'd love Blaster Master: Overdrive for the Wii. It fixes a lot of problems (but not all). I DID beat that one, and it was really good.