Ah, the memories... I can say with certainty that this game was the one I had the most fun mapping.
It was made by a team of people at Konami that went on to form Treasure, which went on to make a lot of 2D games full of sprites animation, rotation and crazy effects that pushed the envelope of how good a 2D game can look.
As such, the stages are varied and a lot of effects were tricky to capture and reproduce on a static map, but the challenges encountered are why I loved this project so much. Among those are the first part of Greece with the reflection on the rising water, the fifth part of Italy where you climb the Tower of Pisa which keeps leaning left and right while moving upwards, the part in France with the rotating stairs and the second part in England where a sort of "hall of mirror" illusion separates the screen in four parts that each scroll with a slightly different speed so you might jump and misjudge where your feet are going to land (sadly, the effect is impossible to represent on the map).
Anyway, I had a lot of fun doing this, and if I ever go back to it, Bucky O'Hare for the NES (also by Konami) featured about the same amount of variety in its stages and thus would be a lot of fun to finish mapping as well.
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Current projects: Metal Storm (NES), Clock Tower (SNES), Ristar-The Shooting Star (Gen), Sonic The Hedgehog (Gen), Sonic CD (Sega CD), Mega Man Zero (GBA), Battletoads (NES), Bucky O'Hare (NES)