Another one you should definitely try is 'Wierd Comic Art Quake2'. 

I used to play Q2 custom maps, and checked almost every recommended one, but I never really liked how Q2 plays.
Overall balance, monsters, slow weapon switching and other timing effect - everything seems off making it much slower and less fun game than older shooters (Doom, Quake, Duke etc) 

i wanted to elaborate a bit on COS3 this morning but didn't have time. it's actually my favourite custom release of any FPS game. the whole thing has an amazing edge-of-seat atmosphere with great use of dark shadows and ambient sounds, and it really plays to q2's strengths by not relying on fast-paced action & horde combat; instead carefully limiting supplies and ensuring every enemy confrontation is properly staged. it's dark, tense and scary, but ultimately thoroughly satisfying.. best experienced in the dark with headphones :)

i last played it mid last year during a break from doom3, which i was in the middle of at the time. there was one moment that struck me as twice as scary as anything d3 could manage, where you navigate a long corridor followed by a huge warehouse type room full of crates, all the time with very limited health, and for a full few minutes you can hear the constant tapping of a parasite's foot. it's hard to make out the direction or distance it's coming from and you'll creep through the warehouse thinking it's round every damn corner, finding out it isn't, breathing a sigh of relief and tensing back up again as you creep forward. such a simple, subtle and effective technique to put the player on edge 

you can hear the constant tapping of a parasite's foot.

that was something i noticed when playing spogsp1... q2 monsters are noisy mofos. i kind of just rolled my eyes near the end of the map with all the iron maiden moaning... thank god they didn't replicate that in q4. :P 

Grinspq2 or grinspq3 that has that heavy alien vibe? 

i have no doubt alien inspired much in both of them :) 

From the screenshots, though I'm sure I've played them.

Time to reinstall Q2? 

but I never really liked how Q2 plays

Yeah, its not as good as Quake. Too slow, not inventive enough with the monsters, although level design was top notch.

I would have liked it much better with less humanoid enemies.

Gladiator, parasite, medic brain in a jar were all cool whilst things like the icarus (why give it legs) and Enforcer (that fall over shooting thing got old quickly) just looked silly.

Gunner was cool I suppose, but he the humanoid should have been few and far between. Imagine if the three basic troopers were instead quadrupedal, or if there was an arachnid crate loader creature.

The Makron was awesome. The shitty railgun head thing (humanoid again) that popped out was like a a Kinder Surprise having a turd in it. 

the shitty railgun head thing was the makron. the thing that held it was called jorg, i think 

Who's fault is it when centerprints are not send to all coop clients? Played id1 with quakespasm (both dedicated server and clients). 

Is quite funny that in PC Quake 2 the final boss is piss easy but on the playstation it was rock hard (not just because of worse controls either) 

Also yeah Quake 2 everything was too slow. The Tanks were pathetic really, compared to a Shambler. And nothing Fiend like either really :E 

But it was so big it got stuck on everything. 

too many hitscan enemies, too many slow, high-HP enemies, and then the ones that were effective were often TOO effective, i.e. the gunner grenade spam. And i don't like the feel of the weapons as much.

My favorite was probably the bezerker, he was kind of a beefed-up quake knight -- rush the player and melee, but with enough health that you had to backpedal as you fought him. That was sort of the model for my rubicon2 dreadmaughts, actually.

I also like the flyer since it requires careful aim, but you also have to periodically side-step his attack, which throws off your aim again.

Parasite was a good panic-inducer, like the tarbaby -- not exactly fun to fight, but a good tool to make the player feel less in control. 

The more I play around with Knights in quake the more I like them. They have just the right health level that they take a few hits with low weaponry but are easily taken in large groups with better gear. Plus the moving attack and range makes them pretty nasty if they corner you :)

I completely forgot about the mutant thingies in Quake 2... man that's just how crap they were. I recall every time you fought one you could either spam it with grenades from above or just screw its movement on geometry as you say :( 

Who's fault is it when centerprints are not send to all coop clients? Played id1 with quakespasm (both dedicated server and clients).

Centerprints are sent to a specified player by design. So blame the QC I guess? On the other hand you could view it as a conscious choice that stuff like "there are more to go" is only sent to the player who's doing something to advance the counter. 

I liked the gameplay. I liked the different style that some enemy were slow but could really fuck your shit up if you got caught out by them (e.g. Gladiator). I liked the weapons and stuff too. 

it may go without saying i also enjoyed it. however i agree the mutant was terrible; i'm not sure how they managed to fuck it up so much given how effective the fiend was. the animation and physics just seem screwy in comparison 

I enjoyed Q2 on another part than comparing it to Q1. I expected more than Q1, as the better graphics and engine did. Then I realized Q1 isn�t replaceable.

The outer base with the waterflow realy blewed my imagination as I spend much more time enjoying the map layout, then fighting monsters. So I died more than once to the incoming attack.

They acted a bit odd, as they were more accidental then hard to fight.
The railgun stuttered me backwards evertwhere.
At least a real backclap from a weapon.
At the end part there was a berseric with two grrlz happily together, which playing the second time were gone.

I just hated that yellow light!
Of course it suppose to be a mars base, but I did everything to get rid of it.
One of the mission packs didn�t have it. 

I didn't like the movement, but there was still great level design in there.

Overall I'd say the game design was the only part off-kilter, although thats also the most important.

I remember the power station and warehouse as being very good.

ReMakeQuake2..? :) 

They sorta dropped the ball on forcing the order of placing the cubes instead of making it open ended. 

movement in q2 is weird... for example, it's possible to slide, almost out of control, down a very gentle slope.
noticed that a few times in spogsp1.
also, if you mantle up when jumping against a low ledge, you conserve your horizontal momentum, which can send you flying out of window or somesuch. very strange decisions were made when the physics were coded up. 

You need a project to apply insights like that to. 

I liked Q2 physics. It was a bit softer than Q1, like hitting edges and stuff, and the double jump bug, but I still liked it in it's own way. 

the thing i mentioned about the mantling/conserving momentum... i think that has to do with the hitting edges and double jump stuff...

because it'll treat the ledge as a step so you keep moving forward, but the ledge is thin, so you end up flying right out a window... i dunno, it's hard for me to explain. :P