I tried the game again, and I like most of the changes you did.
After 4-5 attempts I was finally able to finish the level 4, but is was more out of stubbornness than fun. The only way I was able to do this is using 'pause on buy', which, although very awkward to use, was at least making the game playable.
...And the very next level is "impossible" again, and this time the pause is unavailable since there is nothing to buy!
Please add true active pause, or just decrease difficulty.
The game certainly has potential, but currently it feels like one of those "I Wanna be the Guy"-style masocore games.