Reposting this from /r/Gemcraft. These are a collection of the discovered secrets in Gemcraft: Chasing Shadows. Some of this may be slightly inaccurate, but hopefully compiling all the knowledge here will get us closer to the final answer.
Grey Trees
ReaperGuy on the AG forums figured out GreyTrees, and Seberoth also identified some extra codes. It was discovered that the outside corner squares of the map (zoom out to make them easier to see) are clickable. Various codes inputted will do changes to the game, but so far it's only cosmetic aside from the almost-useless Gift Gems.
The codes are entered with the following scheme (as if they're four corners of a number pad): Southwest = 1 Southeast = 3 Northwest = 7 Northeast = 9
The codes discovered so far are: 11331791 - Grey Trees - To get the achievement, finish any field with this set. 11319773 - Black Orb 13371337 - Spinning tower shots 11379197 - Mossy towers 97713791 - Mossy amplifiers 77919713 - Heavy rain 79797919 - Heavy snow 77311973 - Gift gems 11799397 - Dark monsters 11111111 or any 8 digits of the same number - Mods reset
Assuming up to 8 digits in any given code, there are still over 65k codes to try. I don't think brute forcing these will work. Again, all credit for this discovery goes to ReaperGuy and Seberoth on the AG forums.
Compass
The basic gist is that you need to set all compass pieces to tier 5 and beat the final one that drops the field marker. Rinse and repeat 11 times for talismans and field markers. The third reward is a bugged field marker that prevents the round from finishing. Just manually end it and start on the next compass set. You'll know you have completed them all when the gems no longer show up in the loading screen.
The compasses themselves correspond to the gem tiers you see on the loading screen of compass levels. Teardrop is tier 1, triangle is tier 2, square is tier 3, a "U" shape is tier 4, and an "X" shape is tier 5. Every time the compass tiers reset, the compass correspondences are set to a random orientation, which always follows a pattern of 1-2-3-4-5-4-3-2.
Let me be perfectly clear: The directions on the compass don't matter for any tutorial/description, because where Tier 5 is pointing is random each time you do things such as reload the game, change your skills, or beat a level.
The compass levels, in left-to-right order, are C2, E3, J2, K2, O3, U4, and X7. The easiest level to finish at is E3, with only 24 waves at untraited Looming.
Here is my basic algorithm for setting a compass based upon the gem at the loading screen: Tier 1 - Turn 4 times. Done. Tier 2 - Turn 3 times. Recheck. Tier 3 - Turn 2 times. Recheck. Tier 4 - Turn 7 times. Recheck. Tier 5 - Done (duh).
With this algorithm, tier 2 and 4 always become a tier 3 or 5. Tier 3 always becomes a tier 1 or 5.
The rewards for completion of a certain amount of cycles is as follows: 1 - Field D6 3 - Bugged Field Marker (perhaps supposed to be N7?) 5 - Field O4 (Already acquired through normal progression) 7 - Field P6 9 - Field Q7 11 - Field X6 2, 4, 6, 8, 10th times: Talisman fragments of ascending quality
Missing Fields
This list is FAR from complete or entirely accurate. These are just the notes I have from field markers I have acquired or seen from other sources.
A6 - Complete A4 on Glaring B6 - Complete the achievement "Still Alive B1" D6, P6, Q7, X6 - See compass explanaition above. Y4 (->Y5->Y6) - Complete all waves on X5 without charging up the gem. G4 - Complete the rest of Hex G on Haunted difficulty L5 - Complete L1, L2, and maybe L4 on Haunted difficulty
I Would like some help with my last 4 achievements
Green Vial- kill 75% of monsters with poison.. any tips on how?
Almost - Kill a monster with shots blinking to the monster attacking your orb that would otherwise destroy your orb... I have no idea what any of this means.
Ruined ghost town - destroy 5 dwellings..anyone know what field?
Snowball - drop 27 gem bombs while its snowing ... same as above. just dont know a good field
Green vial is easy. Put max points in at least poison and red and pure colors, all gems dual green/red and in traps and bomb waves till armor is above trap damage. Green ignores armor. There was a field (B,C hextile?) with no place for towers, it's ideal for that.
Almost - I don't know how.
Ruined ghost town - dwellings are these little buildings needing gem bomb to be destroyed. M7 field for me.
Snowball - every field is equally good, just have to play a lot and wait -.-
Almost - Kill a monster with shots blinking to the monster attacking your orb that would otherwise destroy your orb... I have no idea what any of this means.
If there's a shot from a tower flying towards a monster when it reaches your orb, the shot "blinks" to the monster. It's easy to get on F1, just kill all the monsters except one. Let it get banished several times until it's banishment cost is higher than your mana. Have a tower with the orb at the edge of it's range, click and hold the gem until the monster gets right next to the orb, then drop them gem back into the tower.
hello. same as fractal man. (although I enjoyed previous posts about X5 and Y4)
I just beat X5 normally through charging the nodes, and also had battle triats on. Ended up with the chasing shadows battle trait and with Y4. I'm not sure if there is more to it than that. If it helps, I beat it around wave 60, and not a single monster touched the orb. Maybe you have to have a flawless victory? idk