Trying to build a forest puzzle!

I'm trying to build a forest puzzle/encounter for a session this weekend and would love some thoughts or feedback! 

The party is currently in a forest, leaving a witch's cottage who they had gone to for information. It is known to the players that this is a "haunted" forest. They had to fight some ghosts on the way to the witch's cottage, but I want to make leaving the forest a lot harder than it was to enter it. Maybe make the forest literally change as they walk through it.

My plan so far is to have the party begin their walk back through the forest, and end up off path/the forest seeming much thicker than it was before hand. Once the players realise they are lost, I'll hand each of my players a card with a code word on it with instructions to privatly message me the word and and a d20 roll. These words are going to be stuff like "alive", "memories", "mirror", etc. The roles, unknown to them, will be initiative rolls to simply see what we cover first (I am very open to ideas on changing this). The words are going to correlate with experiences each individual have in the forest that they need to get past like loved ones coming "back to life", loosing memories, facing character's fears, etc. 

I'm not sure if I should force a party split (this is something they do on their own sometimes, it hasn't been a problem for dming so far) by seperating one or two to try and make it through on their own, fully seperating them to make it out alone, or leaving them together (unless they choose to seperate).

What I am most unsure of is if that should just be it. That they have to face these fears, the forest trying to convince them to stay, etc, and then once they do they get out. Would something more/different be better/more compelling? I want to shake things up from the normal combat encounters we've done so far. 

Any advice, ideas, or thoughts are much appreciated!!!

You could have each player write down their character's deepest fears on a piece of paper and incorporate them all into the forest somehow. You could also include hallucinations that only one character (per hallucination) can see, causing confusion and possibly splitting up the party, so they have to find each other while confronting their fears. Another possibility is that the forest could become a maze, but the maze is constantly changing. Also, creepy noises and moving shadows are always haunting. If you want combat, shadows, blights, and any undead are good options. Wild magic and dead magic zones could switch things up for spellcasters as well. 

Quote from EmberoftheStream >>

You could have each player write down their character's deepest fears on a piece of paper and incorporate them all into the forest somehow. You could also include hallucinations that only one character (per hallucination) can see, causing confusion and possibly splitting up the party, so they have to find each other while confronting their fears. Another possibility is that the forest could become a maze, but the maze is constantly changing. Also, creepy noises and moving shadows are always haunting. If you want combat, shadows, blights, and any undead are good options. Wild magic and dead magic zones could switch things up for spellcasters as well. 

 These all sound awesome! Thank you for your reply. I absolutly love the idea of individual hallucinations and the changing maze, these are both likely going to make it into the interaction! I also totally forgot that wild magic zones were a thing lol! Defineitely going to look into wild/dead magic zones to incorperate! Thank you again!!