System Shock 1 or 2 might be a good transition. In Painkiller, the user can add buffs with Tarot cards. Also, in the Metro 2033 series, the user can choose various weapons and items before venturing off into the world.

I'd suggest NOLF, but yeah, you know. ¯\_(ツ)_/¯

Hitman?

Deus Ex is quite stealth orientated, you want to sneak by enemies and kill them or take them out when they are unaware. On the first few levels a frontal assault is not good, run away and hide if people are shooting at you. Your probably thinking you can get into gunfights with everyone like other shooters, you'll most likely just get killed if you get noticed and aggravate a bunch of guys. They'll have assault rifles to your mesially unskilled handgun on the first level.

The traquilizer dart gun is good to start out with, it will knock guys out. Avoid robots completely until much later. Try to decide how you want to play and put skill points into the weapon you want, it won't be very effective until you do. Later on you'll be able to get into shootouts and hold your own like more regular shooters and with the armor augment.

Put a point or two into your knife, you'll be able to stealth kill enemies from behind. Also running right up and shooting people in the face with the handgun also works well at the beginning when your accuracy is terrible. Sniper rifle is also good to keep your distance.

You'd be better off shooting his mother.

You can't go wrong with this one. System Shock 2 is amazing! You might want to get some graphics updates though. There are several mods out there that improve the graphics, like shtup http://www.shtupmod.net/ (which just adds higher resolution textures)
or rebirth: http://www.moddb.com/mods/system-shock-rebirthhigh-poly-pack (which changes some 3D models - not my taste, but some like it)

Bioshock, the Jules Verne ripoff, with the repeating scenery, 6 bad guys, and a predictable storyline. I think I actually fell asleep half way through :o)

Shadow warrior 2013 version for my money, mindless violence!

Although if op likes rtcw then what about call of duty 1 and 2, or medal of honor original set?

Your not a bullet sponge rambo like other shooters until you slowly upgrade your self to be like that, if you want to play like that. Enemies are as strong as you are at the start, maybe stronger with their equipment.

XIII

They're both as repetitive as one another haha. Great scenery and atmosphere that rip off Verne was exactly why I loved it though haha. I love that old school scifi/adventure/horror stuff. The first two Call of Duty games and Medal of Honor Allied Assault and maybe Airborne would definitely go down well I think.

I would recommend Bioshock. (Full disclosure, I don't like it)

Deus EX plays more like a RPG than shooter to me (you have to actually upgrade to be able to shoot properly) and Wolfenstein is a straight up FPS goodie so the reason for this recommendation is because Bioshock has this very light blend between RPG and FPS elements that I think makes it a balanced transition (upgrading, shooting bit, deep plot, atmosphere, etc).