Did anybody else feel Metro 2033 was incredibly similar to Half Life?

Having just played through Metro 2033 in preparation for Metro: Last Light, I couldn't stop thinking how similar it was to Half Life. Everything from the environments, the atmosphere, the sounds 4A used, amongst other things. I have no problem if this was deliberate. I see it as more of a homage than a cheap knockoff.

Did anybody else feel this way when playing through it?

Sorry if this is a well known thing. I'm a bit late to the party with this series.