Grid16 is a collection of minigames, much like Four Second Frenzy (review here), and like Four Second Frenzy, it is brought to you by the prolific jmtb02, which means that you'll see a well-polished game with not necessarily particularly deep gameplay. (Unlike Four Second Frenzy, however, in which each game has its own separate designer and hence separate aesthetic, here all the games are designed by jmtb02, which gives the game a much more unified feel.)
The basic gameplay concept is very simple: one out of the 16 minigames starts, and you play it for a few seconds. If you survive, you are switched to a different minigame; if you fail, then that minigame is removed from the rotation. When you've failed on all 16 minigames, the game ends and gives your rating in three different categories of game skills, which is kind of neat. As you go along, the speed multiplier increases, making the games considerably more difficult. Grid16 doesn't even give you the courtesy of flashing an instruction before starting a game; you're plunged right in, with some text of varying helpfulness scrolling along the top.
The main problem with Grid16 is that it has the reward system backwards. Games that you're bad at you will get quickly eliminated in, meaning that you don't get much of a chance to improve in those games. This is especially frustrating when you don't even see a minigame until the speed multiplier has already been cranked up a few notches, giving you even less of a chance to survive your first time. (The minigame selection is always random, so you may see one minigame several times before you see the first appearance of another.) Conversely, you can do well by being proficient in only a few games, since once you're down to just a few minigames left you'll just keep getting those. In the extreme case, you could probably just practice to be really good at one game and ignore the other fifteen entirely. This kind of defeats the purpose of having so many minigames, really. The other flaw is that one of the games is bugged -- at least in some Flash versions (it works fine on my home computer, but not other computers), it's possible to fall through the floor, which makes the game awfully easy. One other thing to watch out for is that each minigame always picks up from where you left it off last time, which can be surprisingly frustrating -- you can't just plan to survive for your three seconds (or however long it is), but always have to be thinking ahead.
As befits a jmtb02 production, the production values are solid -- the graphics are simple but clean, and the music is nicely intense, but there is the occasional typo. This is not an easy game -- even getting the easy badge is not quite trivial, and getting the hard badge is exceedingly difficult. Unless, alas, your computer is slow, in which case it's much, much easier. Overall, while I generally enjoy the minigame concept, the fact that I really don't get to enjoy the whole game but just end up playing the same few minigames repeatedly is kind of a disappointment, so I wouldn't rank this quite as highly as Four Second Frenzy.