Perhaps even better - Obelisk: Devilkiller, also by Craze? It has the same kind of non-linear 'metroidvania' style of gameplay, but also has a 'Burst' system that reminds me in some ways of some of your systems. It also has a larger roster of characters you can exchange with swappable equipment so there is some strategy of preparing for specific battles.
Have you tried Visions and Voices (also Craze)? I don't think the mechanical systems can touch my other recommendations, but it is interesting for pitting the player against attrition and a sort of time limit, with lots of optional exploration that furthers the characters/story. There is a tension between taking risks and playing it safe that I liked, reminding me of a good roguelike.
And for a generally different take, but another short experience with what were really memorable and fun battle mechanics for me, In Search of Immortality by Indra and Fomar. There are levels, but they only increase the 'slots' you have to modify your characters.
These might help inspire you if you seek to take some of the "tightness" out of your games ('overdesigned fixed combats' I think you said), either by trying out less linearity in the fixed combats (Obelisk and Wine and Roses) and possible loadouts, or maybe by playing around with more meaningful random encounters (V&V or Immortality)... I hope you also realize that the mechanical 'puzzly' tightness you have been offering has its place, and you are doing it *really* well.
For example, I would say "Slimes" has a similar focus on a gauntlet of battles with a (slowly expanding but basic) toolset. And I enjoyed it, but I was eventually feeling "solved" with that game's strategy, while Ocean OI had me pissing myself laser focused in every battle. Perhaps not for everyone, but a niche that exists and you are equipped to fill well!