Questions & Answers about Хотя я устал, я всё же пойду в парк вечером.
Хотя means although / even though and introduces a subordinate clause.
So the sentence is structured like this:
- Хотя я устал = although I am tired / although I got tired
- я всё же пойду в парк вечером = I will still go to the park in the evening
Russian normally uses a comma to separate this kind of subordinate clause from the main clause, just like English often does.
Устал is the past-tense form of the verb устать = to get tired / to become tired.
Here it means something like I got tired or more naturally in English I am tired depending on context.
Уставший is an adjective/participle meaning tired as a description, like a tired person.
So:
- Я устал = I am tired / I got tired
- Я уставший = I am tired (more descriptive, more adjective-like, often more colloquial in some contexts)
In this sentence, Я устал is the standard and natural choice.