(Disclosure: This site contains product affiliate links. We may receive a commission if you make a purchase after clicking on one of these links. Read our affiliate disclosure for more info.)
Homefront is on sale for $4.99 (75% off) at GMG. Use the voucher code GMG25-1BW0K-K1A3G to save an additional 25% off, which makes the game only $3.75.
It uses Steamworks, so Steam activation is required.