* Missing subject: "You" is implied but needs to be stated explicitly.
* Run-on sentence: There are too many independent clauses strung together without proper punctuation or conjunctions.
* Awkward phrasing: "So could go out" and "almost finished entire project" are not grammatically correct.
Here are a few ways to revise the sentence:
Option 1 (Concise):
> You worked hard all day, finishing most of your project, so you could go out that night.
Option 2 (More detail):
> After working hard all day, you managed to almost complete the entire project, allowing you to go out that night.
Option 3 (Emphasis on work):
> You put in a long day of work and almost finished the entire project, so you deserved to go out that night.
The best option depends on what you want to emphasize in the sentence.