About a day ago, I posted some ideas for every theme except Folklore: https://ldjam.com/events/ludum-dare/54/$371557/ideas-for-each-theme

Here are some more ideas!

Shelter

• Build traps to keep enemies from entering your shelter

Break the cycle

• Same idea as shelter, but with continuous waves of enemies and an end goal of protecting your shelter so that no enemies can ever enter

Underground

• I don't really have much else to say on this one... you could take almost any other theme and apply it to an underground setting

Strange machines

• Defend against waves of unfamiliar robots

Paths

• Level-based game where you can skip levels by taking certain paths

Signal

• Keep defending yourself until you see/hear the signal? (It's pretty basic, but I don't have a lot of ideas for this theme)

Overgrown

• The player and/or enemy has extreme muscles

Sanctuary

• Same idea as shelter

Salvage

• You are stuck in space and must find a way to get home by salvaging the remains of the rocket

Reflect

• Narrative about self-reflection

Locks and keys

• Same idea as paths but with the addition of keys

Keep the light on

• Enemies only spawn in darkness, so use your light to keep them away

Tiny Creatures

• The main enemies are tiny insects with the power of murder hornets

Limited space

• The level design prevents you from dodging attacks, so you must use your skills and items and can't rely on movement

Absorb

• Your health goes down by itself, and you must regain health from sources (like plants or creatures)