Help me find a tile-based puzzle+shooter game, like a darker Chip’s challenge

I've already posted this on other subreddits, and many, many forums in the past, but nobody seems to know what I'm talking about. HELP!

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Platform: PC

Genre: tile-based puzzle+shooter?

Estimated year of release: between 1995 and 2004 (I guess)

Graphics/art style: top-down, tile based, dark maps, sort of had a cyber/industrial feeling to it though the graphics pretty simple. Black background, gray or maybe blue maze walls. On the right hand side of the screen there was a panel with ammo and other stuff and at the bottom right a tiny map of the whole level with moving enemies (tiny dots).

Notable characters: you play a white square with a face. You have to kill enemies who are also squares of various colours depending on the type (I remember blue and green squares…and possibly white ninjas?). 

Then there was a special bad guy, that may have been called lava worm or blood worm. Made up of 4 or 5 bright red balls and running around like a train. I hated it.

Notable gameplay mechanics:

• it had a lot of things in common with Chip's challenge (https://www.moregameslike.com/wp-content/screenshots/chips-challenge-1-44051-1.jpg), e.g. the coloured keys/locks and the slides (green in the pic I linked, but they may have been red/yellow in my game), though it looked more modern than Chip's challenge
• You could fight the bad guys by shooting them (limited ammo) or with dynamite
• To clear a level, you had to kill all enemies (and collect all keys?)

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Here's my caravaggio-like rendition of the main character and bad guys: https://preview.redd.it/ijal959rif791.png?width=1499&format=png&auto=webp&s=5e8e3023d3a63567c42530ce90b08002121f6f98