Puzealth is a game of puzzle and stealth. although making strategy is optional.
You have to sneak through the level and collect orbs.
Once you collected all the orbs then the portal will open, which will take you further.
The game gets difficult when guards are on the post, avoid them or assassinate them is entirely up to you.

Some time assassinate them are the only option.
As you master your stealth skills, clearing levels will get easier and easier. Even if you are not a skilled assassin.
You can always make a strategy by calculating the guard's position and timing to use against them.
Create chaos by letting them see you, although it is only recommended if you are a stealth master as games get even more hardcore.

One more thing there will be more than one type of guard, each with different abilities and capabilities.
Some of them are faster than others. Some are spontaneous. Some with higher alerts and some are immortals.

Then there will be traps. But don't worry some levels you can get special abilities but to handle them,
you still need to master your stealth skills and be good at assassinating enemies.
Some of the abilities that will be available in later levels are: -

SuperSpeed - Double the speed of movement, double the speed of assassinating guards,
double the speed of door unlocking, but nobody still can't call you a double agent.

Burning Shield - No matter which type of guard catches you, they will be destroyed instantly.

Distractors - activate them then hide to clear your path.

The game is designed in a way that there are more than one way to clear each level.
So it is up to you how you treat this game, as a Puzzle game, Stealth game, or Strategy game.
It is about how you play it.