If you've purchased a Nexus 7, you might already be well-aware of the fact that it is literally the perfect size for a touch gaming system. What you may not know is what games are actually worth your time and, more importantly, your money. That $25 Play Store credit is probably burning a hole in your pocket, and you're just itching to figure out how to spend it. I'm going to give you the rundown on which games you should definitely be looking at - old and new. And because everybody has different tastes when it comes to gaming, we're giving you a real list - 15 of our top picks. This list contains only apps that are currently compatible with the Nexus 7, so keep that in mind - some great games like Plants vs. Zombies still need to be updated for compatibility (thank EA's typically unapologetic laziness, as none of their games will be making this list).

#1-5: The Cream Of The Crop (You Should Probably Just Buy This)

#1 Dead Trigger, by Madfinger Games ($0.99)

Dead Trigger is probably the most fun I've ever had playing a mobile game that was actually designed from the ground up to be used with a touch interface. It's that good. Does it have in-app purchases? Yep, but they're done right.

It's about shooting zombies. That's really it. It takes advantage of some Tegra 3-specific effects and other goodies on the Nexus 7 too. One word of caution, the app's in-app purchases don't currently work on the Nexus 7, and it occasionally crashes. An update to fix these issues will probably come soon. Either way, it's an amazingly well-done game that I think everyone will enjoy. I firmly believe it's the best game available for Android right now.

#2 Final Fantasy III, by Square Enix ($15.99)

I know what you're thinking. SIXTEEN DOLLARS, FOR A MOBILE GAME!? Yeah, well, this is like the USDA Prime filet mignon of paid Android games. In terms of raw amount of content, fun factor, and engrossing story, it literally does not get any better than this. Final Fantasy III is a port of the highly popular Nintendo DS remake of the 1990 RPG original. If you don't know what Final Fantasy is, I doubt any of this will convince you to buy it.

This was the second purchase I made with my $25 Play Store credit, and it was definitely worth it. The game's touch controls are fantastic (and persistent throughout), there are no bugs, no crashes, and everything works great.

#3 Where's My Water? / Where's My Perry?, by Disney ($0.99 each)

Listen, these may look like kid games on the surface, but they're two of the best physics-based puzzle titles ever to come to Android. I like them a lot more than Angry Birds, and they give you a lot of bang for your buck in terms of gameplay hours. Where's My Water? won so many Mobile Game of the Year awards in 2011 that I'd be loathe to put it anywhere but high up on this list. Where's My Perry? is the sequel, and while it does feel a bit more like an expansion pack of sorts, it's still great fun. I'm packing them together as one "game" because they're so similar.

Where's My Perry?:

#4 Great Big War Game, by Rubicon Development ($2.99)

If you haven't played the prequel to Great Big War Game, Great Little War Game, the $0.99 is definitely a worthwhile investment. Great War Big Game is a lot like GLWG, except better in every way. More content, better graphics, more features, and a brand-new online multiplayer mode. It's a pretty complex strategy title, but it's easy to learn through the 50-mission single-player campaign. This is the best strategy game on Android, bar-none.

#5 World Of Goo, by 2D BOY  ($4.99)

And yes, it's yet another physics game, but this one's based on building stuff. World Of Goo is one of the most visually appealing games I've seen since Machinarium (which, sadly, is not compatible with the Nexus 7 at the writing of this article). The worlds are dark and beautiful - it feels like you're playing through some kind of strange Pixar-short-meets-Psychonauts dream. There are plenty of levels, a great soundtrack, and even a story! If you haven't picked this one up in the many promotions it's been a part of, you probably should.

#6-15: For Your Consideration (Awesome, But Maybe Not For Everyone)

#6 Shadowgun THD, by Madfinger Games ($4.99)

Shadowgun is a pretty good game. And it's probably still the most cutting-edge 3rd-person shooter on Android from a visual standpoint. It's also fun, and if you buy the THD version, it looks even prettier on Tegra 3 devices. The game has been widely popular, and if you're looking for something to kill four or five hours with, Shadowgun is definitely entertaining. And you'll probably just get a kick out of the quality of the visuals your Nexus 7 is capable of producing.

#7 Minecraft - Pocket Edition, by Mojang ($6.99)

If you've never heard of Minecraft, you probably don't pay much attention to gaming in general. The block-based world builder has been an absolute smash hit; in fact, it's probably indie-gaming's greatest success story. The mobile version for Android has an absolutely stellar 4.4 star average rating with over 500,000 downloads. If you like Minecraft, you're going to buy this. If you don't, hey, maybe it's worth seeing what the hubbub is all about.

#8 Jelly Defense, by Infinite Dreams ($2.99)

I know, I know. A tower defense game? Come on, that's like, the most played-out genre ever. But Jelly Defense is the best tower defense game I've played, hands-down. The worlds, art, and animations are, dare I say, adorable. And the gameplay itself is just fantastic - the developers very carefully balanced each and every level, unit, and consumable. Let me put it this way - Robo Defense (Android's most popular TD game) is to tower defense games what Morton's Salt is to... salt. Jelly Defense is that fancy pink Himalayan stuff you get at Whole Foods.

#9 Metal Slug 3, by SNK ($6.99)

It's Metal Slug. What else is there to say? If you ever played the popular run-and-gun sidescroller, you know why it's a cult classic. Metal Slug 3 is one of the more popular titles in the franchise, and this version includes Bluetooth-based coop gameplay. It's a tad pricey, but the reviews are generally very positive, and the game itself, well, it's Metal Slug, man.

#10 Sonic 4 Episode II, by SEGA ($6.99)

There have been previous Sonic games for Android, but they've been plagued by poor touch controls and compatibility issues. Sonic 4 Episode II's controls are much more usable, and the game has undergone a complete 3D makeover. The visuals on Tegra 3 devices are astounding, and you get all that classic Sonic sidescroller gameplay, to boot. The game itself is reasonably long (and actually quite difficult). Additionally, you can use Bluetooth or Wi-Fi to do cooperative Sonic and Tails play, just like the good 'ol days. You can also pick up Sonic CD and Episode I if you're wanting to catch up on the story (if you own Episode I and II, you get a special 4-act expansion featuring Metal Sonic).

#11 Kinectimals, by Microsoft ($2.99)

This is another one of those "if you play it already" sort of titles. A lot of people (especially kids) love Kinectimals on the Xbox 360, and the Android version has debuted to absolutely stellar reviews, with an average of 4.5 stars. Kinectimals is essentially a virtual pet game, and the Android edition allows you to unlock exclusive content (new pets) that can then be used on the Xbox version. For $3, it's not a bad deal at all for a game with extreme visual polish and lots of family-appeal.

#12 Osmos HD, by Hemisphere Games ($2.99)

Osmos HD is a port of the popular PC indie strategy title, and it doesn't disappoint. The touchscreen interface actually makes the game a little more fun, in my mind. It's a relatively slow game, and requires you to carefully decide and ruminate on your tactics in an amoeba-eat-amoeba world filled with tranquil music and vivid colors. It's relaxing, engaging, and addicting. I can almost guarantee you'll love it, if you have the patience to actually sit down and think about a game you're playing.

#13 Sprinkle, by Mediocre ($0.99*)

Sprinkle is another casual physics-based game, but it's also one of the most beautiful we've ever come across. Tegra devices get enhanced effects with Sprinkle, and the water physics in this game are just jaw-droppingly gorgeous and realistic. It's one of my go-to time-killers, and it looks even more beautiful on the Nexus 7's larger display than on my One X smartphone. *It's on sale at the moment for $0.99 (50% off), so this is definitely one worth picking up now.

#14 Reckless Racing 2, by Polarbit ($4.99)

Do the top-down arcade racers of days past make you oh-so-nostalgic? Then Reckless Racing 2 should be on your "must-buy" list. It's the latest installment in Android's most popular top-down racer franchise, and it's chocked-full of awesome content, tracks, and online multiplayer.

#15 Air Attack HD, by Art In Games ($2.99)

If you were as much of a fan of top-down aerial combat games when you were kid as me, Air Attack HD brings back some of that classic gameplay in a modern package. It's not terribly long, but the visuals are great, there are a ton of enemy types, various weapons, and Tegra-specific visual enhancements. Each of the 10 missions has a boss with a different fight mechanic, you can blow up almost anything, and it's just plane fun. It's an oldie, but a goodie.