Here is some free assets found on the net
The use of these asset mostly have condition.
For some, creator must be add in the credits, for others, you can't sell the final product.
The conditions are nearly always on the creator website. Serach a little and if you don't found, contact the webmaster.
The condition for our asset :
- modification and sales are ok.
- must be add in the credits :
"Laurent Goethals (Andreil Game)" in the right location (graphism ou something else)