Speaking of kicks, I recently realized there is a sliding kick too. You have to be running forward then press the attack and then crouch buttons quickly (in that order). It's a bit difficult to do. I actually haven't managed to hit an enemy with it yet. The jump kick (which they call the bicycle kick in the game) seems more effective.

That nailgun, that attaches enemies to the walls.... They make wonderful pieces of art afterwards...

There is the punches, which is with holstered weapon + melee (mouse 1).
Then, there is that Krav Maga style weapon melee attack, equipped weapon + melee (mouse 1).
There is the Jump Kick while being stationary/motionless, jump + melee (mouse 1).
The Forward Flying Kick, while running forward, jump + melee (mouse 1).
And the sliding kick, while running forward, crouch + melee.

A good variety/mix of good old unarmed goodness. That the sequels so dearly MISS. 2 didn't even have HALF of those moves, and 3 ALMOST NONE!

I always found it very hard to believe, plus annoying and irritating, that an older game contained more variety and gameplay elements, compared to newer and more technologically advanced titles. The ability to save whenever you wish, to carry medkits etc, are DEARLY missed in the sequels, too...

Penetrator, pistols and railgun. Shotgun is outstanding. But despite the fact that it's a corridor shooter's corridor shooter, you're seldom in very close. So I didn't really use it much.

Penetrator. Used it together with the Shotgun most of the time. The 3rd weapon is "depending on mood".

I used to love the shotgun but recently I exchanged it with the pistol akimbo because it's way cooler. Then boringly the most common good assault rifle (the green one) and then either the rocketlauncher when it gives me one because it usually means their is a mech coming and otherwise the particle sniper rifle, mostly for the big armored dudes.

When I was young I used to think about how awesome games would be when technology got better. Well, technology got better but game developers for some reason decided to make their games worse.

Yeah... The "graphics disease". The better the graphics and technology become, the worse AI, gameplay, game world and game mechanisms become.