I both agree and disagree on the sound front... Yeah it can be cool and tbh even octoshmup currently uses sounds ripped from a HL1 mod for weapons and stuff (the specialists! represent ;_;) but maaaan I still wish this game were being made "for realz" so that's where my disagreement comes in, also some of the sounds, most notably the HL1 ones are erring on the side of "too iconic/memorable" so they will forever belong to Hl1 and feel out of place anywhere else. But otherwise, meh.. It's not such a big deal really I suppose? It's not like you're trying to make money from SD or anything.