Locks and keys - can generate some decent gameplay mechanics, but feels to generic (a lot of games have doors, keys, etc)

Keep the light on - This theme forces you to use light in your game. Not all games genres even have light

You are the enemy - very "game-jamy" theme. Even too game-jamy. It's a typical theme with a twist, but I think it was overused over the years

Underground - enforces a specific setting. I don't want to play 20 games taking place in underground caves

Sanctuary - same as above. Playing every game inside sanctuaries will become boring

Folklore - another setting enforcing theme. This time it makes all game take place in old stories

Signal - potentially creative take for games. Signal can have so many meanings that we will end up with a lot of diverse games

Tiny Creatures - too limiting. Half of the games will be Tamagochi clones, other half will be Pokemon clones

Reflect - another theme with multiple interpretations. It will make most games original and diverse

Metamorphosis - not as good as "signal" and "reflect", but it still has a potential for many different games

Echoes - I didn't come up with a game idea on the first sight of this theme, so I believe it will make us create some unexpected and creative games

Decay - on the one hand it may generete some good gameplay mechanics. On the oher hand I think that it forces creating mostly damaged, corrupted enviroments which will result in less diverse games

Pick your poison - another theme with mixed opinion. May potentially generate diverse mechanics, but also has a "downgrades, not upgrades" vibe

Consume - this theme can have many different meanings and interpretation, making it a very good theme

Witchcraft - another setting enforcing theme. I don't like it

Shelter - this theme has been suggested for at least 5 years. Please stop. It's boring

These are my opinions about round 1 themes. What are yours?