Thanks to the author: しんわ (shinwa) for the modifications, though the difficulty is still high, so some life-saving or invisibility features were added.
Double Dragon 2
Modifications:
1. Press START + ↑ = skip level
2. Press ↓↑B = energy wave
3. Press ↑↓ = fast 8-hit combo
4. Standing kick changed to fast 5-hit combo
5. Jump kick frames changed to spinning kick frames, and holding ← or → during the kick allows fast movement
6. Holding ← or → during the spinning kick allows fast movement
7. Press SELECT + ← or SELECT + → to execute a knee strike directly
Author: しんわ (shinwa)
——————————
Added life-saving feature, by 悠然小赐
☆★☆★☆★☆★☆
Double Dragon 3
Modifications:
1. Anytime Up + A = call 2P spinning kick attack
2. Anytime Up + B = call 2P fat character for 2 mid-air kicks
3. While jumping Up + A = ninja mid-air sword slash
4. While jumping Up + B = ninja mid-air kick
5. While jumping Down + A = fat character fish dive headbutt
6. While jumping Down + B = fat character mid-air 2-hit kick
7. Down + AB = directly perform spinning kick; can also press Down + AB in mid-air
8. Up + AB = ninja backflip, can bounce off walls; if not touching a wall, pressing “Down” allows a ninja air sliding attack
9. Mid-air normal kick = fat character sliding kick
A. Press A while dashing = teleport and track double nunchuck attack
B. Press B while dashing = teleport and track ninja kick attack
C. Down then Up + A = ninja shuriken attack (need fast button combo)
D. Down then Up + B = throw weapon directly (need fast button combo)
E. Up + START = skip level
F. Press START = show health (displays enemy remaining health in hexadecimal, shown at the bottom right)
10. Spinning kick changed to two-person combined spinning kick, and holding left or right allows fast movement during execution
11. Adjusted enemies in each level, especially strengthened BOSS fights; experience it yourself
Note:
1. To run this modified version properly, please use the emulator included in the zip file.
2. In places with high platforms, the enemies' HP cannot be displayed (only three places: after taking the elevator in level 1, the initial part of level 4, and the initial part of level 5)
3. Since skills are integrated, the ninja and the fat character cannot use them; even if used, they will revert back.
4. Two-player mode is not possible; even if two people play, Player 2 will overlap with Player 1, making it basically uncontrollable.
5. Tested through to completion, no points of consistent crashes found. Author: しんわ (shinwa)
--------------
Added no health reduction, invisibility
by 悠然小赐