Game & all video renders well. But menu, text & HUD is stretched (same as LLL). Not a problem.
(PLP screenshot with bezel effect, special attack view)
1. Do Lock-Up Fix * (if you have the problem).
2. SoftTH (DX9 x86).
3. Shortcut/launcher argument -d3d9.
4. In regedit, Find (Ctrl+F) "Prince of Persia" (checkmark Keys & Match whole string only). You want this entry: ...\Software\Ubisoft\Prince of Persia\#.#\Engine. There may be two copies, but the 2nd likely emulates yours edits.
5. Edit values of Engine key (in Decimal Base): AspectRatioOverride ### ([your width / height] x 100, rounded to three digits); for ScreenResolutionWidth & ...Height, enter your massive resolution (####, no border).
(more common view)
NOTES:
B. Enforcing DX9 is a minimal loss, as DX10 game is nearly pointless for this art style.
C. * Lock-Up Fix. Run (path-to-game)\Launcher\Launcher.exe. Correct the settings (single-screen), checkmark Widescreen, Quit.
D. Windowed works (DXWnd & same regedit changes), but looks very bad.
E. If suddenly game won't start, must revert game to stock (undo registry edits & remove SoftTH). Then do Lock-Up Fix, start game, quit. Then spread game again.
View guide for general help with the instructions.