Linear, but quite fun especially for the time. Exploration component is really good because the game needs you to leave no stone unturned, and your are rewarded for it..
They actually use the select button, which is not something I use today. Also got stuck on corner pixels occasionally.
This story is great. Metal Gear is always off the rails when it comes to story, but it always adds to the experirence, the first game being no different than the MGS series.
No way to ID doors with cards, unlike misssion Impossible with the switches
Co-op Style: None
this is exclusively a one player experience
Exploration and the story, but mainly the former. You are rewarded with new items, process, etc.. In very quick bursts for exploring all the things and under all the rocks.
Exploration of the base and the jungle was awesome and rewarding. Also felt good to git gud as I played the same areas over again. Story was a nice addition too.
The Less Fun
Without an FAQ this would have been a bit of a grind for, but not bad.