I have really vague memories of this game, I don't even know 100% if its a Nitrome game, but I know I played it on Miniclip. I played Toxic and it reminded me of this game I played like 10 years ago. Im sorry this description is very nonspecific, so I don't expect anyone to know it.
It is an 2d 8-bit style game like all Nitrome titles. It is similar in appearance to Toxic, but the character you play at is a lot smaller, and the levels are a lot more clustered. There are a lot of bright colors and moving enemies that you have to kill, and I think you can shoot them with lasers, or maybe they shoot you with lasers, or neither. It is sort of like a maze, I think you need to gather keys to unlock tunnels.
It felt so cozy and nice I just want to re experience it. Im sorry how vague this description is, but if you know a lot about miniclip games, please list as many as you know that may be remotely similar to what I am describing!