In need for upgrades? Or you want those pesky runes? Well there are always a few tells when a secret is nearby.
First of all never forget this:
Thats quite literal
When you see health bonuses they will be pointing to a secret or a secret might be nearby. On the other hand armor bonuses will usually mark the main level route.
Like in classic Doom, the basic is being aware for suspicious textures. But also blood spatters in the walls or background are usually present with secret paths. Or just anything that looks like a door.
oddly shaped like a door….
Sometimes its the same texture, but there is blood…
And after all that. What are runes for? Well they unlock a map in the overworld. And inside that map, they unlock special doors. Each one of these doors contains a reward. The more runes the door needs the more powerful the reward.
What could be behind door number 1? Well its not one of those regular upgrades