My current build (quite fun), a quick-draw gunslinger:
Strength 5
Dexterity 10
Agility 6
Intelligence 7
Constitution 3
Charisma 3
Perception 11
Skills:
Guns maxed
Mechanics maxed or close - for crafting nice pistols
Electronics a lot of points - for crafting nice pistol electronic parts, e.g. Smart module
Dodge/Evade close to maxed
Lockpicking/Traps/Throwing - decent amount of points
Mercantile - some points for being able to barter for nice components
Feats:
Gunslinger
Recklessness
Paranoia
Rapid Fire
Point Shot
Aimed Shot
Kneecap Shot
Bullet Time
Trigger Happy
Gun Nut
Steadfast Aim
Sharpshooter
Critical Power
Specialization:
5 points in Bullet Time
10 Points in Critical Power
Weapon:
crafted .44 Hammerer with Smart Module and Rapid Reloader - about 24-125 damage, with +52% damage with special abilities, and AP cost of attacks reduced by ~25%, and chance to refund AP with every attack
Armor: just using a galvanized overcoat for now, with a nice shield emitter. Seeker goggles with +12% crit chance.
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So the idea is, I have a very high initiative (5 + 10 (Dexterity) + 6 (Agility) + 5 (Paranoia) + 7 (Trigger Happy) = 33), which means the vast majority of fights, I get to go first. This is the quick-draw part.
Then, I can use my abilities to get a LOT done during that opening round. With 10 Dexterity, 32AP for .44 Hammerer becomes 26AP, with Rapid Reloader pistol part, goes down to 19AP, eventually I want to raise Dexterity a few more points and get it down even further. Activating fully specialized Bullet Time reduces AP costs by 50%, so a regular attack costs about 9-10AP, and Rapid Fire (which is 3 attacks) costs 15AP or less. Throw in some Adrenaline, and you can do a ridiculous number of attacks in that opening round before the enemy can do anything.
But then you got the damage. So my current pistol is about 24-125 damage, then adjusted with the high Guns skill, it becomes about 78-267. Most damage is done via abilities (Rapid Fire, Point Shot, Aimed Shot, Kneecap Shot), and the smart module on the pistol increases that by 52% now. Then I already have 37% critical chance now (should go higher later with more equipment/feats). And where this build gets really interesting is the critical damage:
Pistol = +125% critical damage.
With Sharpshooter = +155% critical damage
With specialized critical Power = +265% critical damage
So once you adjust all this in, I've already had some crits for over 1400 damage (after damage mitigation).
Once I add in the leather armor with +crit chance, improve my Seeker goggles to higher crit chance, and get the Scrutinous feat, should be over 50% crit chance, with a crazy number of attacks per round.
The only downside is my build is squishy af. If I don't kill everything that moves in the first turn, I often die.