Nicktoons Unite offers some decent fun for fans, even though it's short.
It starts out with Jimmy inventing an invention that opens portals to other dimensions. Unfortunately, Jimmy's idea is stolen by Professor Calamitous after he spies on him. Calamitous forms a team with Denzel Crocker, Vlad, and Plankton and calls themselves the Evil Syndicate. When Jimmy finds out their plans, he recruits his own team with Timmy Turner, Danny Phantom, and Spongebob to stop the Evil Syndicate. I thought this story was decent, and it gave this game a plot.
In each level, players go around with two Nicktoon characters destroying three portals that release enemies, and collecting four nano chips to complete each levels. In addition to this task, there are areas only certain characters could reach. For example, Jimmy could reach high areas using a jet pack, or Danny could turn into a ghost and go through certain walls. However, sometimes there's an obstacle that needs a different character, other than one of the original two chosen at the start of the level. So there are teleporters in each level that let players change characters when they need to. Levels also have doors that need teamwork to unlock. Finally there are boss levels in this game as well. The game is short and I finished it in less than a day. Still, I had fun playing it.
The graphics are pretty good. The backgrounds and levels match the show their based on well. Characters look almost as good as the characters on their shows. The sound is also good. I thought some of the music was pretty good and went well with each level. The sound effects were good, but they were nothing too special.
Overall, I enjoyed Nicktoons Unite, even though it was short. My recommendation, if you're a fan of one of these characters, then try to check it out. It may offer some decent fun for you. However if you're not a fan of these characters or want a longer game to play, then you might want to look into another game.