Glad you liked my time on Erebo haha :)
I see the improvements indeed. From walking in a creepy forest to exploring 3 different and nicely made biomes, that's a big step already!
About your question, maybe a bit more interactions with the environment? If I'm walking from A to B, I'd enjoy having some "obstacles" here and there, not monsters or traps (I mean why not, but it depends on the game) but things to climb, doors to open, paths to create (like putting a fire out or repairing a bridge or something). Just to be clear, I'm not talking about minigames here (I'm not a big fan of those). Something else would be events during the exploration. Each planet had a bit of that already. You start walking and suddenly a threat is near, it's good, and there are lot of other things to imagine to keep the player on his toes. Examples: The sandworm appears close to me while I'm walking and destroy a house or something ; A sudden lightning hits a quartz pillar making it fall and nearly crush me ; Vhar'Zul plays with me, talks to me while I'm walking, actually deciding if I need to be killed or not.