I offer my strategy that eventually got me the Impossible badge. Finish the main levels quickly, because the more turns you take, the less gold you get. Get seven units with Cantrip (lightning) and four units with Shield. This maximized my options to move a lot while also gaining ~2 defenses per turn. Two of the five pawns only cost 4 gold to get Shield on them; Optimally, you buy two of these to save gold. When buying Cantrip, prefer the stronger units over pawns. Before moving, always check if you have enough moves to reach a safe place on the board (a tile where you survive with the least health loss). Keep track of the remaining cards in your deck if you take risks with Cantrip units. Defeat those units first that do not spread further units or blight upon defeat. Abuse the game mechanic that turns your pawns into queens when you reach the top row. (Your queen retains the original pawn's abilities.) And if you lose a single health before the Gauntlet, restart.
Tip: Quitting a game with the Quit button does not break a win streak. To get the badge, you can get any 100 badges of all 120. The award counter on the Hard badge is broken, so you should count your badges manually after a while.
I think Elwyen has a secret power that caused the death of her parents. Maybe not even she knows about it, but she's a Water-elemental siren, and her parents were frozen in ice, so it would make sense.
I cleared level 14, and as I suspected, not the intended way. You can completely ignore the second bat and the first ghost the following way: Normal jump to the right, lick the first bat while slightly above him. This will send you flying BELOW the second (and third) bat, but the game counts it as slightly above the fourth bat. At the right time, press jump to land on the fourth bat, right up to the fifth bat, then right up to the skull. This also ignores the crevice on the right, but you need to switch directions mid-air while jumping. The most difficult part is landing the jump on the fourth bat, but it's much easier than the way I saw videos about. Good luck!
The timeline makes no sense. We know from Ada that this happens after the Invidia Games, but then why is Amber still a child? The Invidia Games happened when Amber was an adult, ffs.
For the Powerful Red achievement, the best setup is H3 Wasp Hull, S4 Power Booster, and the most powerful option from everything else. During the game, go for the green Speed Boost icons and try to avoid vision limiting bugs and magma rocks. Start using your boosts as soon as you reach 0 m and never stop.
Easier way to get the gotta-go-fast badge: Get a decent height, then start falling down while you still have boost. Falling speed is higher, because it's boosted by gravity.
If you have problem winning the Twin race, you can turn character speed to 2x in the Options. Other than that, you need to have the unused arrow-tile above the small island show UPWARDS. Hope this helped~
Hint for the Twin puzzle! Make sure that the one block above the little island you land on first points UP. If it points DOWN, some other arrows will throw you in wrong directions.
 "Ratmaze 2")
 "Pawnbarian")
 "Unproportional")
 "Zilch")
 "MARDEK RPG: Chapter 3")
 "Greedy Mimic")
 "Zombie Minesweeper"){kind=logo}
 "Nano Kingdoms"){kind=icon}
 "It's Just TIC TAC TOE")
 "Medieval Cop - How the Grump Stole Christmas!")
 "MegaDrill")
 "Kick The Critter")
 "Reach the core")
 "Mine of Sight")
 "Race Time"){kind=icon}
 "Learn to Fly 3")
 "Dojo of Death")
 "Medieval Cop -The Invidia Games - Part 3")