Mission selection lets you (re)play any mission you reached in the storyline so far.
Starting with some basic training.
Ingame menu lets you switch the vision mode when available.
Every mission has its preliminary briefing that sort of fills for the lack of ingame text.
Our hero can hang from the ledge obviously... forever.
Oh goody, there's a treasure to plunder in here.
Cracking the safe, as all similar actions, has time limit.
All that's missing in the scenes such as this is a 007 theme song.
Disabling the broadcasting dish.
You can use a spy camera any time in the game, which may be helpful for scouting the area before you proceed.
Checking mission objectives.
There's a time for sneaking and there's a time for action.
Using thermal vision lets you see the burried mines.
GameBoy Player screen lets you change game's sharpness level, screen size, and even switching the cartridge without need for shutting the console down.
When trying to use stealth, timing is of greatest importance.
Knocking out the guard will render him unconscious only if you do it from behind. Otherwise, it'll require a few more kicks and you'll probably bite some bullets in the process.
Some missions will be dangerous even without the guards.
What if he steps on my fingers? No, game developers didn't think of implementing such details, though.
Using smoke grenade will render unconscious enemy guards, but strangely enough, not you.
Running fast while the floor is collapsing with your each step.
Thanks to your monkey skills, you won't feel too hot.