I think before you add more stuff and mindlessly apply suggestions, seemingly without thinking and without understanding the structure and reasoning behind them, you should first define what camera angle you want for your game. Show the schematic for what you intend there, so we can do a better job at pointing out flaws regarding perspective.
The tree looks flat and small. The base should curve along an ellipse. The suggestions of ellipses between the shades in the crown seem too sharp at the left and right ends, leaving the impression the tree is projected at a different angle compared to the house and also making the crown look not as roundish/ball shaped as it was presumably intended.
Again, draw a simple side view of it first, define the camera angle, use parallel projection to get a consistent appearance across all assets. Do not wing it.