Nozomanu Fushi no Boukensha

Both have main characters that are skeletons and they both have the same general fantasy adventurer tropes. 

,Both a that turn into a skeleton, Both with skeleton appearance  

Both are slow paced fantasy anime that focus on world/character building over generic op MC tracks down the big bad and somehow kills it. The choices characters make are logical and there aren't any lifeless joke characters to pad out the story.  

both MC gain new powers and second chance at life after narrowly avoiding death in a hidden dungeon they accidentally stumble upon solo levelling is more action oriented and high tension undead adventurer is more chill and slow paced 

both MCs are reserved and stoic, a bit dense, low-level by the guild's standard but highly experienced adventurers, both MCs have their face hidden under a helmet/ mask for almost the entire anime. goblin slayer has a party, undead adventurer adventures solo 

If you like a fantasy about a character growing and getting stronger with actual fights, watch this 

Similarities: Both MCs become a monster and try to return to humans Both MCs have a female companion on their journey Both series take place in a fantasy MMORPG setting Both series have MC fighting monsters and players Differences: Ququ is CGI chinese vs Fushi is 2D japanese Ququ is an video game isekai vs Fushi is non-isekai Ququ MC is not overpowered in the beginning vs Fushi MC is overpowered in the beginning