1. Ditch what doesn't work: In Bound in Blood -- a prequel to the original cowboy FPS -- what's most notable is perhaps what hasn't made the journey from the original game. There's no more crummy fisticuffs, no more holstering your irons to do a special move, no using a whip for frustrating platforming and no weapons that fall apart after use.
Developer Techland has, as William Faulkner suggested, killed their little darlings, and the Juarez followup is so much the better for it. If something you treasure was left by the wayside, I apologize. I can, however, assure that it was, in fact, terrible, and you were wrong to like it. Wrong.
2. Take what does work and make it work better: The strong narrative thread of Juarez has returned for BiB and is even more engrossing as you follow brothers Thomas and Ray McCall (the latter, you'll remember, starred in the original game) as they seek out love and fortune during and after the Civil War. It's an expertly written and performed (and surprisingly mature) tale, and one that I won't ruin with any details here.
The basic shooting mechanic has been honed too, with each weapon, from Ray's trademark dual pistols to Thomas' rifle, feeling really authentic. In almost every mission, you'll get to choose whether you'll play as Ray, who tends to rush headfirst into battle, or the slightly stealthier Thomas, who uses his lasso to get the perfect sniping vantage point. Either way, it's a real thrill to see whatever brother you didn't choose backing you up the whole way (and actually contributing!).
As in the last game, there's a lot of variety, with a trench crawl followed up by a sniping segment followed by some horseback riding, etc. But the pacing's much improved, without a lot of Juarez's filler.
3. Add some new things that work: Though the last game also rewarded you with the occasional super-strong attack (called Concentration Moves in the Juarezverse) they've been completely rethought for BiB. Most notable is Thomas' attack, which has him killing anything in range as long as you hold the right trigger and fan the right stick with your palm like it was a pistol hammer. If you want an immersive Western experience it doesn't get much better than that.
Ooh, scratch that, because it actually does get better with the brilliant quickdraw duels. In these one-on-one battles (which place the camera right behind your holster) you'll circle an enemy with the left stick and try to keep him in the center of your screen. Meanwhile, you'll have to keep your wandering right hand close (but not too close) to your gun in anticipation of the bell toll that marks the start of the duel, your cue to close the final inch between hand and holster and blow your foe into next Tuesday. There wasn't a single time I heard that bell that my heart didn't jump into my throat, and, though I've never been in a pistol duel myself, I imagine that's pretty close to the real thing.
... OK, so I'll admit there's a fourth, less recommendable step that BiB takes, which is "invent some new stuff that doesn't work." The lasso climbing mechanic is cruddy, the cover system rarely works exactly how you want it to and I constantly wanted more inventory control (like the ability to sell back the upgraded weapons that I had purchased or swap them between brothers).
But those rough edges never stood in the way of my enjoyment of this gritty, completely entertaining experience, one that I hope serves as a sign post for devs tasked with following up games that they didn't quite nail on the first go-round.