The game mentions a soldier's will influencing whether they have a gift or not. Since you can only test a soldier once, does that mean promoting a soldier a couple of times before testing might produce a different outcome than testing them as soon as they arrive? So far all of my psionics were majors or colonels at the time of testing, so that seems at least plausible, though I've noticed a certain degree of determinism in the game, and it would be silly for soldiers to have the ability to develop a gift but not the ability to get tested again. Do others factor play into whether a soldier has the gift or not?
I just reloaded my game about 10 times trying to figure this out and I have some results. I tested the same 5 colonels, randomly mixing them together in testing, every single one of them was psi gifted, but not every time. It is not determined when the character is created, the fact that the colonel with the lowest will became gifted but only once out of the 10 times points to randomly gifting the soldiers being tested but adding their will score to the roll.
Simply put, if you want your favorite characters to all be psychics it is easy, it will just take a long time, you will have to put them through testing by themselves or with rookies added in and keep reloading until they become psychic then work on the next character. I have gotten 2 out of the 3 as gifted in about half of the 10 tests, but I was not able to garner a 3 for 3.
Did a couple of experiments that netted about 8 psi soldiers so far: 1 Col, 3 Maj, 1 Lt, 3 Squaddies. 2/3 psi soldiers everytime as I lack the patience. UPDATE: I managed to get 3/3 psi soldiers in a session: 2 squaddies and 1 major.
It requires about 4 savegames max and a lot of patience. Firstly before putting any soldiers in the psi labs, create savegame#1. Then put in 3 soldiers then create savegame#2. Wait for the 10 days ignoring any UFOs or missions.
Note down if the soldiers are gifted, if not go back to savegame#1 and pick another set of soldiers and overwrite savegame#2 until you get a hit.
Once you found the gifted soldier load savegame#2, replace the rest and create savegame#3 then wait again for 10 days and reload savegame#2 rinse and repeat until you got a hit. So you'll have 2/3 of your soldiers guaranteed to be psi gifted.
I got squaddies with ~50 will to become psi soldiers and I only test the assaults, support and heavy classes, snipers when I am actually bored.
This way I am not writing off majors and colonels with 90 and above will.
Conclusion: the soldiers are randomly selected to be psi gifted when they are entered into the psi lab. So in theory it is possible to get at least 60% psi soldiers with this method.
Hope this helps.
Psionic Soldiers 100%
Make 1 save for back up in case you mess up. Make 1 save for testing the soldier.
The game determines if a soldier has psionic power the momment of testing. Attributes might give them a higher rate of success but I'm not really sure. Every soldier can be gifted with enough chances. Patience is needed though.
Step 1) Save 1 file with no soldiers being tested.
Step 2) Add 3 soldiers to each psi test slot (we'll call them soldier a,b,c)
Step 3) Save under a slot 2
step 4) Skip all ufo attacks and upgrades for 10 days see if any of them are gifted. If non of the soldiers is gifted head back to "save 1" and repeat step 2. Do this until you find a gifted soldier.
step 5) You found soldier c (for example) has a gift. Load "save 2".
Step 6) Remove Soldiers a and b. Replace soldiers a and b. (This can be done with same soldiers and same order, it doesn't matter) DO NOT REMOVE THE GIFTED SOLDIERS!
Step 7) SAVE and Skip ahead 10 days recheck to see if you have anymore gifted soldiers. repeat step 6 till all 3 slot have gifted soldiers.
step 8) Once all 3 slots are filled with gifted soldier reload one last time fight, kill off ufo or skip ahead (that's up to you). After 10 days all 3 will be gifted.
P.S. can be done with one save slot but I make 2 just in case I mess up. Hope this helps GL ~link
I have found that you can take soldiers who were already in testing, who came out ungifted, pull them out of testing before the project end, retest them later with recruits, and have them come out gifted. This indicates that gifted/non-gifted status is not set in stone at the time of entry, but rather at completion of testing.
Test done using - XCOM: Enemy Unknown version 1.0.0 on the PC
I placed three colonels into psi testing. Several days and much Earthly heartache later, two of them came out gifted. I reloaded to a save before completion (but AFTER I had already placed them in testing), removed my ungifted colonel from testing before completion and fast-forwarded. Upon completion, the same two were gifted, and the third slot was empty, of course. I then entered my previously ungifted colonel into testing and in one of my subsequent reloads my previously ungifted colonel came out gifted.
I would note: the original game setting has the chance at 4 (%?). This is in the ini file as psi_gift_chance=4. HOWEVER, I've changed this to 99 (reducing the time to 10 hours, as well, via hexedit). This does NOT yield a lot of psi folks (and considering I have them all hyped to like 200 wil, this was kind of surprising). So the "save and reload" is probably your best bet, as the "direct cheat" doesn't work. I'd also note that almost everything in the ini file is in the exe file, and it is there that you must change it. But it is byte counted / checked on runtime, so you have to use the "spaces" given in each section (if you delete or insert, you should to do the opposite somewhere in the same section of the ini - just keep track or simply replace what is there and don't insert or delete anything). If you aren't familiar with hexeditors, then I wouldn't suggest doing this at all. If you are: remember to SAVE SAVE SAVE your original game file exe.
I took 2 assaults, we'll call them x1 and x2, and 1 sniper. None gifted. reloaded and instead of putting in x1, x2, and sniper, I put in x2, x1, and a sniper. all three came out gifted. So, I did what anyone would do. I reset the game and tried it again.
x1, x2, and a sniper. None gifted (again) x2, x1, and a sniper. All gifted (again) Sniper, x1, x2. sniper gifted Sniper, x2, x1. x1 gifted
It seems the position of the soldiers certainly affects the outcome in regards to the other soldiers you put in.