What gameplay? Since when lazily popping out from behind geometry shooting shit, then lazily popping back in counts as gameplay?
SP Q2 doesn't have much gameplay because it boils down to mechanically repeating the same thing over and over again without ever requiring you to modify your behaviour and without needing nearly as much reflex or manual dexterity as fucking Baldur's Gate or Wizardry 8 (hey, at least in Wiz you sometimes have to act fast and precisely before TB combat starts if you don't want to get raped).
Q2, is an FPS, FPS games rely primarily on enemies to provide gameplay.
Q2 enemies suck (threat levels in 0-10 scale):
1) Guard (blaster) - threat level 0 - fairly mobile and is endowed with almost adequate reaction speed, but shoots easily dodgable projectiles rather inaccurately and dies if you look at him menacingly enough - can be killed reliably with 2-3 blaster bolts or one shotgun blast.
2) Guard (shotgun) - as above, but can actually hope to cause some damage sometimes due to hitscan weapon, threat level 1
3) Guard (MG) - as above, it differs in that it cause damage in a more annoying manner, still harmless, threat level 1
4) Enfagcer - threat level 0, preposterously slow reaction time presumably due to having around seven different safety locks on his chaingun, not better in melee where he swings his chaingun like some ludicrously slow club. A bit sturdier than guards, but can be killed reliably with single SSG or any explosive, easily stunlocked with automatics. If he can't be killed fast for any reason, his preposterously slow reaction gives you plenty of time to get behind something solid which will then be treated to impotent stream of bullets after which you can emerge and shoot him again.
5) Fagrasite - nuissance enemy, threat level 1 (average, 2 at close range, 0 otherwise) fairly fast, relatively sturdy, can hit reliably from close distance dealing fair amounts of damage over time, but no long range attack meaning it can be dispatched cheesily from distance.
6) Goner - Pretty much the same as enfagcer, except it can lob grenades that may force you to move a step or two away from your favoured spot right behind the edge of geometry, delaying his demise. Twice as hard but easily staggered, meaning you don't risk retaliation between two consecutive SSG blast needed to put him down. At distance rockets, grenades and railgun work just as well saving you the hassle of having to run up to goner and shoot him in the face. Rapid fire weapons are also effective. Threat level 0, in some circumstances 1.
7) Ironic Manboon - like goner, only weaker, fires single, easily dodged rockets instead of series of grenades and lacks hitscan weapon, making it threat level 0.
8) Derpserker - slightly harder goner, with fast and erratic movement and only melee attack. Gets stuck on everything. Easily staggered and should still die if treated with two SSG blasts, provided all pellets hit. It's melee attack is easy to dodge so recommended tactics is running up to him and emptying barrels while dodging melee attack, then repeating. Rapid fire weapons are almost as good. Ranged attacks not recommended because faggot zigzags all the time making them more frustrating than just 2xSSG in the face. RG works well enough, though. Threat level 0, 1 if fought in cramped space, on walkway above some environmental danger or if it's spawned behind you. You should still be able to avoid any damage if you keep cool head, even when fighting multiple derpserkers at once.
9) Faglier - nuissance enemy, threat level 1, can cause light damage with it's rapid blaster attack if you somehow miss the tell-tale noise, run into a wall, or forget that it's dumb as a brick and try to dodge in any more elaborate manner than running in single direction. For this reason it's best popamoled from behind corners. Recommended weapons include SG (less spread than SSG), later HB. If you have good eye, RL or even GL (for extra lulz) can be used to take out multiple fagliers. MG works, but it's disappointing due to excessive spread.
10) Turdchnician - like faglier, only harder and therefore more annoying. Thankfully makes bigger and slower target. Needs something stronger than SG due to lots of HP, so choose whatever works best at given range, threat level 1.
11) iCarus - like above, only even harder and slightly more agile, therefore more annoying. RG or HB recommended. Threat still level 1.
12) Fish - know the saying about shooting fish in the barrel? Threat level 0, the only thing working in its favour is its wonky hitbox.
13) Medic - threat level 2, in direct confrontation 0. Would work better if you couldn't gib corpses and if he didn't suck so hard in combat. Looks cooler than most Q2 enemies.
14) Gaydiator - threat level 3, maybe even 4, almost adequate reaction time, lots of HP and low RoF, but quite powerful hitscan attack. Best popamoled. If popamole is unavailable you should exploit its laggy aim and move a lot to avoid damage. In such circumstances RG works nicely, but other ranged weapons are adequate too. You can probably tease him in melee for great effect too, by moving in and out his melee range, but I haven't tested that.
15) Mutant - threat level 0, would actually be a decent enemy with its high mobility if it was a bit sturdier, smarter and didn't get stuck on geometry all the time. Unfortunately in its present state it can be gunned down effortlessly before it even closes the distance. SSG works like charm, so does HB. Other weapons are also great.
16) Tank - threat level 0, horribly sluggish, uses three different (but equally worthless) weapons - wide-angle MG spray that rarely hits you and even if it does it deals minimal damage due to spread, blaster that is easily dodged and triple rocket launcher that has to be deployed and aimed at which point you're safely hidden behind something solid. A real damage sponge which, along with its extreme sluggishness, predisposes it to be popamoled for minimum hassle and ammo consumption. If met in cramped environment with no cover it should be quickly dispatched with CG - you will likely kill it before it manages to actually aim any of its weapons at you.
In the open you could probably just circlestrafe it with blaster, but why would you want to waste so much time on a shitty enemy in a shitty game?
17) Brians - threat level 0, too slow to actually pose any threat, especially with melee only attack (tentacle rape), energy shield makes it a bit of a damage sponge, though.
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18) Fellow spaz mehreen - threat level 2, repetitive cries may cause irrational behaviour due to severe annoyance, followed by injury or death, no direct offensive capabilities.
Problem?