Difficult is a great way to describe this game. You have a timer, a ton of enemies on a single floor with replacements regularly arriving, and you must find the key to ascend the stairs and reach the next floor. Also, this key may be either buried or a monster may be carrying it. I played this as a kid and find it has not become any easier in my old age.
You can defeat enemies by digging traps and covering them. Enemies that fall in holes can also be walked over without harming Boomer. Fortunately, there are many upgrades scattered that you need to uncover or walk into to grab. These are weapons, upgrades for your speed and digging capability and detectors for the keys. The game is not entirely unforgiving.
The game uses a password system along the way. After you manage to beat a few floors and reach a boss, you will be very grateful for that password you need.
Controls: 5 / 10
I think this was a bit of a drawback in the design. While controls were reasonably responsive, something about them made the game feel a bit laggy.
Music: 9 / 10
This is one area I will give the game. Each tower section has it's own music, each of them well-made pieces of music.
Sound Effects: 7 / 10
I find myself like the sound effects, as well. Boomer's dying scream as he is it fits well with the game. Nothing comes off as obnoxious or annoying. Digging sound gets repetitive... reptetitive... reptetitive... The digging sound gets repetitive, however.
Graphics: 5 / 10
The bosses are reasonably done, but the tower floor are flat, too consistent and the enemies are not very well animated either.