HELP AND OPINIONS ON SILHOUETTE STAGES

I think you're on the right track but need more analysis as to the reason of the effect you're going for. It seems a bit weird that the foreground-most objects (the vines at the top? I'm not counting the HUD as that needs to be coloured) are the most well-lit, while the very next layer (the gameplay area) is completely black.

As is seen in the DKC screenshot, important objects in the gameplay layer have colour for tracking reasons (the characters' clothes and the enemy's eyes). It bends the natural rules of lighting for gameplay and aesthetic purpose but everything not directly needed for gameplay is still following the laws of proper lighting and where the light is coming from.

In your screenshot it's not hard to tell where there's land and objects and where there isn't, but I think it just doesn't look good because the gameplay area appears as though it should be lit from two light sources (whatever's lighting the foreground and whatever's lighting the background). So having the gameplay area in shadow, breaking the rules of lighting, is a stylistic choice (which is fine. great, even) but unlike how other games implement this (often used in factory or stormy areas) I just don't think having the foreground-most layer entirely well-lit isn't a good idea.

To toss my hat in the ring - the secret to good silhouette stages is high contrast between the black foreground and the background. That's the core of it.

Shovel Knight is a fantastic game, but the dark sections of Specter Knight (while I personally had no issue with them) were some of the most prominent complaints I read about the game. Because contrast only occurred with the blue walls and lightning strikes it meant that those unfortunate players that might not have the keenest eyes were caused loads of deaths and undue frustration. The main problem isn't necessarily that the stage design in those sections was poorly constructed, but mostly that the darkness was for style and added challenge that detracted too much without adding enough flair. All because it was too dark.

Silhouette stages should first and foremost be about amplifying the visual aesthetic of your level, without detracting from the gameplay whatsoever. The black outlines should add a treat for the eyes and maybe throw players for a bit of a loop, but not be difficult. The stage design should be relatively simple. If player's can't see and they die to something, then it isn't really their fault, and they'll get angry.

Therefore these stages usually work the best when there's a proper strong light source that illuminates it - that's how light works after all. So in your images, the fact is your background is far too dark. You need it to be sunset, or foggy, or with spotlights or something. These stages also tend to work best when you have a simple gameplay setup: The more clear your game objects are and the more they have a recognizable silhouette, the more clear the outlines of the stage. Last thing you want is anything that seems to define a solid entity and isn't: Case in point being the vines in your picture. Its not like you can't have them since they're so high up but if they are removed it makes the image simpler and therefore stronger. There's less clutter that players have to keep track of. Just make sure that at the beginning of the stage if there is anything that players can walk through, make it clearly identifiable and give players a chance to interact with it in safety.

My recommendation is - have the foreground straight black, and have a color gradient for your background that starts bright at the top and gets cooler toward the bottom. Tweak the colors until you can completely see what's going on in the stage and you should be set. Those mountains at the bottom either need to go, or only have them as a black outline, rather than filled in mountains.