Another thing is that there are several bosses that you'll fight in Metal Gear. Learn which weapons work against them. The graphics in Metal Gear and excellent. There's plenty of detail, color, and animation to satisfy any video game player. They added a lot of variety in the music.
Some tracks are just plain cool and others are very suspenseful.
The drums and percussion are what you'd expect from a Konami game. The music is very well done. As far as the challenge goes, there's plenty of it in Metal Gear. There are TONS of items that you must find, mazes in the jungle in which you must use the correct route to get further, and absolutely loads of death traps awaiting you around the complex. You'll want to make a map of the game because it is BIG with lots of exploring.