I got one of those $5 credits as well for buying a code for a PS Plus membership, but all the games in this promo are for PC. Which two games did you get?
Foul Play and Marlow Briggs and the Mask of Death. Sadly (but understandably) the credits can't be stacked. I got $25 worth of credits, but I know I won't be buying 5 games during this.
Update: Well, I played both games and here are some very early impressions. I suppose the best theme for these games is "Poor Man's," because neither of these games are original. They're basically copies of other games with a slight twist.
Let's start with Foul Play, or as I call it, "Castle Crashers dodging." Basically the game looks and plays like CC, with the twist being that rather than having an energy bar, you have "Crowd Support." The "plot" is that you are a character in a play, where for some reason violence is preferred over acting ability. You get credit for chaining combos and avoiding getting hit, but then again that could be said in some way for nearly every beat em up made in this decade. Also, the action is very repetitive. This isn't a game you binge on or beat in one sitting. You play it for like 30 minutes max, because the action is so repetitive that it can't really carry itself for very long. That's not to say it's bad, but unless a major gamechanger comes, it appears that you're basically doing the same things in Act 1 Scene 1 that you do in Act 5 Scene 5.
The other game is Marlow Briggs, or as I call it, "God of South America." The plot can be summarized as, hot archaeologist girl brings bad-ass BF to work site, girl gets in spat with boss, BF tries to defend girl, BF is killed with mystical weapon that brings him back to life and the two of them go about exacting revenge. Actually now that I think about it, the plot is akin to that of "Splatterhouse," a game that came out in 1988. Anyways the actual gameplay is basically a copy of God of War, down to the Quick Time Events that have you pressing buttons that appear on the screen where they are on the gamepad (X on Left, B on right, A on bottom , Y on Top.) If you played any GoW game and decided to use the "staff" weapon, you've essentially played this game, although this game isn't quite as polished. Again, it isn't bad, but the gameplay is so derivative that it's impossible to not take notice.
Neither of these deficiencies are enough to make me stop playing either game, but I have put my expectations in check.