So there is sort of a visibility issue with enemies offscreen to the south, which makes it so players prefer to hug the southern wall in order to not be taken by surprise and to be able to aim with guns effectively, which further hinders visibility because of gates along the south wall, so this suggestion is twofold.
1. It would be nice if nearby offscreen enemies were represented by avatar bubbles along the edges of the screen, roughly indicating their position. Ideally, the bubble should highlight with the familiar red spikey 'about to attack' animation when they are about to attack, in order to help players prepare for unseen assailants.
2. Visual obstacles that abuse the camera angle are kind of brutal to deal with. It would be fantastic if there were a transparency bubble around the player, enemies, and items so that they could be seen regardless of what may stand in the way of seeing them. Particularly frustrating is the southern monster gate that glows bright purple and effectively obstructs the entire bottom two tiles of the screen near it, including the boundary between the nice, safe, floor and the deadly spikes in the final arena room, but also rather frequently hiding less mobile enemies like healers, and valuable items like health.
Anti Aliasing. Deal with it.
No, the bubble suggestion is fine, but if you know there's an enemy offscreen to the south, aim south and fire. With guns, autotarget makes it ridiculously easy to hit almost anything. And with swords you can just charge them and murder them all.