Particle effects obscure map objects
I have attached definitions for all available game plugins, however this is an issue with the engine rather than the plugins. In short, given that you have one of these addons installed, bloodsplatter effects are rendered over items and enemies, among other things. This can be quite unpleasant when dealing with enemies in large quantities, as they will be hidden by the splatter -- especially when backed up against walls to which the splatter has attached.
Included are screenshots of the issue affecting Chex and Heretic. I have attached definitions for all plugins, however.