Thanks for playing, and I appreciate the feedback! I’m not sure if you played the archived 7DRL submission or the current version, but I made a few changes recently to balance out that particular issue. You can (r)elease souls to gain essence, which is a better deal than having them knocked off you by attacks at 0 essence. You can also now pass through all monsters’ squares, although of course you’re leaving yourself open for attacks.
The flip side is what you mention about being able to overrun enemies at full essence. There’s a few mechanics that are meant to balance this, but they need tweaking. The essence cost to go through passages is meant to force a risk/reward tradeoff (entering a more dangerous area with less essence, but also progressing faster). The auto-targeting mechanic sometimes forces you to destroy dying monsters that are in a place that’s too dangerous to hit.
My next round of updates will include adding more monsters and tweaking level generation. Right now there’s a bit of a “feast or famine” situation with vermin. There’s also some more soul effects I have planned that will increase tactical options. The Slow effect needs a substantial nerf, as well. And there’s one mechanic that was always intended but I never got around to implementing – dying monsters should actually, y’know, die eventually, so you can’t just leave them around as essence caches.