Here's how you can purchase both of those titles for only $7.50!
Both of those titles are listed for $5 each, but you can lower that price to $3.75 by using the code DS25 at checkout. The list price is $19.99.
Please note that a free Steam account is required to activate and play those titles.
On Steam: 91% of the 19,647 user reviews for Metro 2033 Redux are positive; while 93% of the 15,475 user reviews for Metro: Last Light are positive.