Before anyone else says so, I'm making thread on this b/c the existing threads containing walkthroughs and tips for TLS3:UC do not properly address the achievement section of the game. Also, I did not put this on the Wikia page either since it seems not many people are building it it fast enough.
With that in mind, the purpose of this thread is to find the requirements for the secret/difficult achievements of TLS3:UC. I myself don't know all the requirements, so hopefully people with experience inform everyone else.
Out of the 54 achievements, I found the following either difficult, impossible, or confusing to complete under certain circumstances.
1. MASTERFUL - Level any skill to 100.For this achievement, 100 skill points must be allocated to a single skill category. This does not include bonuses added through attribute points or smart skill bonuses (during a level up). In other words, keep leveling that single skill (or reading skill books) until it won't let you level it anymore, and it should unlock.
2. PILLS HERE! - Use 15 bottles of pills.Pain Pills only add to this counter. No Zzz is not counted toward this achievement, despite also being pills in a bottle. Additionally, Pain Pills may be hard to find for some players. I found only 15 bottles myself in a single play-through. So the only advice I have is increase that Luck stat and hope for the best.
3. FORGETFUL - Forget to level up.Easy to do, if you know what do (b/c this is a secret achievement). Level up your character twice without distributing any points on the Character screen.
4. NO VACANCY - Fill up storage at safe house to max.Also easy to do, if you know what do (another secret achievement). Try to fill your storage box at the safehouse passed its maximum capacity.
5. DEATH FROM ABOVE - Kill an enemy while airborne.Secret achievement. Kill an enemy mid-jump. I did this with a melee weapon.
6. OH COME ON - Force and break a lock with +90% chance of successful break.Secret achievement. It's self-explanatory, but still very hard to get. You also need a high Security/Luck stat level to get +90%, so that means you have less than a 10% chance of breaking the lock (opposite to forcing the lock open).
7. MASTER LOCKSMITH - Pick 30 locks successfullyTo be honest, I don't even know if there are even 30 locks to begin with. If there is, beware that some pick-able locks have keys to them, so be wary of picking up any keys before you find out if you can actually lockpick the lock it goes to. Additionally, you may have to forfeit the other achievement where you have to force open 3 locks. Hopefully the rumor of additionally expansion packs for this game is true, in which it might have the extra locks we need.
8. BRAINS BEATS BRAWN - get 90% by security more 1% by strength in pick lock.Secret achievement. In other words, pick (not force) a lock when a +90% chance to break lock is available (with high Security/luck skill).
9. BRAWN BEATS BRAINS - gets 90% by strength more 1% by security in pick lock.Secret achievement. If I knew, I'd tell you. But I don't. Someone mentioned that you need a +10% success chance of forcing the lock, and then actually beating the lock. The trouble is, I can't find such a lock. I tried having a low security/luck skill, but the lowest success rate I saw was +24%. If you know the answer to this one, please step forward.
10. SECRET ACHIEVEMENTDon't be worried when you see these achievements (there's 3 of them, I think). These are actually storyline-related, and will unlock eventually for you.
11. Other secret achievements, with readable-title.Other than the secret achievements above, the other secret achievements are also are storyline-related, and will unlock eventually for you.
All in all, the only achievement not accounted for is #9 BRAWN BEATS BRAINS The ones I omitted seem pretty self explanatory, so I didn't list them. Hopefully, this thread will be wrapped up shortly and completed, so someone could put up a complete achievement guide on the Wikia page. So once again, this thread is a walkthrough only for the achievements of TLS3:UC.
I've beeten the game twice already too but i had a problem... i got the 50 cal. sniper rifle but no 50 cal. ammo so I was thinking about getting rid of it. (same with RPG too) but then i found out if u have a rare gun that takes a certin kind of ammo all u do i have the gun on your back and start killing the zombies with backpacks with a melee weapon (like the katana or battleaxe(the weapon u need ammo for is on your back still)) and even on the first airea u can get RPG ammo and 50 cal. ITS MARACULUS!
@fighter5345 I gave the RPG to my partner it is much easier plus the 50 cal in my mind sucks that just me but you can give that to your partner instead because they never run out of ammo. Here check this out http://gamewalkthroughscheatstipssecrets.blogspot.com/2011/12/weapons.html