I want to start off by saying I read these somewhere between 2010 and 2015 (I'm not sure when exactly), and I was reading these on my mobile. Back then the site, for me, had a white background and mainly used grey and blue for colours elsewhere. I know 100% it was a wikia site and this is the only good creepypasta one I know of.
With these, I only have faint descriptions (these are probably forgotten and/or deleted, but worth a go):
1. A short creepypasta based around GTA 4 about the character being trapped forever
2. A 5 paragraph story where someone goes between a hallway in something like a hotel to a forest and at the end mentions reading the first word of each psragraph to say 'You Just Lost The Game' (or something like that)
3. One where a boy (not sure on age, I think is maybe 10-15?) is led into the woods and at the end turns into a tree (for some reason?)
4. A story similar to one about not jumping into the lake on Sundays (I can't even find that now), but the ending seemed different, in the one I remember, at the end they are writing about being inside the creature.
2. I have definitely read or listened to a narration of that story during the past couple years, but I also don't remember the name.
3. While not exactly like what you described, could you be thinking of this story? Alternatively, there is Where the Birches Lean, in which a boy of that age is lured into the woods and turned into a tree, but that's a very recent story. You could also look through our Nature category for specific titles, though it's a rather big category.
