Thanks for the feedback.
The color palette and line styles are definitely a work in progress. I actualy have 9 shapes and 9 styles. I limited to these set of 3 for this phase, as it made the rudementary grid generation I use fairly simple with a decent challenge.
But one of the interesting phenomena of the mechanic is, IMO and my experience, the player gets 'blind' the more they play. e.g. if you start focusing on the oragne double line shapes, alot of times you can't see the other matches because your brain tunes the rest out, and a form of tunnel vision occurs. Part of the challenge is to keep your mind open and resisting that tunnel vision. I agree the colors and shapes are not ideal at the moment, but I would be curious how much of your experience was due to the failing of the design's chosen shapes/styles/colors, or how much is that psychological effect is responsible. Not sure how to even measure that.
I have thought about different types of progression and possible levels or specific patterns. However, what I am currently going for is something closer to classic Geometry Wars style, specifically Pacifism mode. Where the game session should be short (60-180 seconds) and its more a sandbox that gradually increases in difficulty and the player sees how long they can last; Ideally where they sorta zone out and let their brain unconsiously play. Unknown if I'll be able to achieve it as well as some other games have, specifically Pasifism, but that what I am currently going for.
Currently my main concern for difficulty is avoiding making dead ends during the generation. I only want dead ends to exist due to the player inadvertently creating them themselves and then running into them. Currently dead ends are created during maze generation.
As far as your score; due to how the multipliers keeps stacking, it actually doesn't take long to go from 60k point to 500k to 3000k points. Sometimes its a matter of 10 seconds longer just to get a much higher score. i.e. the score is compounded so the natural tendendcy to compare the scores linearly is deceptive. e.g. You may have gotten 60k points one run, then the next run 500k and the only difference was you went a littel faster and lasted 5 seconds longer. I plan on exposing alot of stats on the game over screen. I am always a fan of stats and letting the player choose what they want to be judging thier progress on.
Thanks again for the feedback. Later this week I have it planned to address some of the things you brought up.