An original Umihara Kawase (a Japanese platforming game developed by Studio Saizensen for the Super Famicom) developer has released video of the first two prototypes of the game, showcase drastic differences between early versions of the game and its final release.

While the YouTube video of the prototypes is in Japanese, the auto-translated English subtitles are actually pretty accurate and gives enough information to be useful for curious developers.

It's always fun to see what changes throughout development, especially for games published outside of America. 

A Twitter thread by developer Brandon Sheffield (and Gamasutra contributor) explains how the design and name of the main character was decided from the start, but because of uncertainty around what kind of game it would be, two prototypes were developed first on the X68000 (a computer exclusive to Japan). 

In the first prototype, players could dig trenches and connect them to water and flood enemies out. There was also a pump used to attack them, but it was never implemented due to trouble with the water/trench system. After lots of trial and error the developers realized it wouldn't work.

Instead, the team moved on to prototype two, which went in a completely different direction. Rather than digging and draining water, players would connect and break open doors in order to flood certain areas.

There was an issue in prototype two where enemies were too easy to defeat, so in an attempt to figure out a more technically interesting way to attack enemies, the developers tossed around the idea of shooting something out of a wire to capture them. 

Thus, the final version of Umihara Kawase was born.