Good:
- Very nice lighting system
- The cramped environments make you feel very claustrophobic
- Lore hooked me quick
Bad:
- PDAs are always shown in the exact same order, I'd prefer if every body had its own PDA, that way you could even use a body to warn the player of an upcoming hazard
- Death is too quick and punishing, I'd recommend spikes just take a bit off your oxygen rather than sending you straight to the beginning, or add some checkpoints (e.g. when you get the depth upgrade)