Don't worry, the Hardest Game Ever 2 is not a sequel to this game, and that's a good thing. Even though it poses as an insanely frustrating game, the truth is that Hardest Game Ever 2 is reasonably approachable even for a gaming dilettante.
Gameplay consists of a variety of scenarios in which you have to tap the screen in a certain rhythm, for a certain number of times, or in a certain amount of seconds. Depending on your performance, you will be graded. Just like in school, an F won't do, but anything above will let you pas to the following level.
Some challenges are harder than others, and I didn't notice any progression in difficulty. Perhaps that's because you need to use different areas of your brain go through each one and, depending on experience, one might do better at response time than at pattern recognition and so on.
The challenges have amusing themes. For example, in one, you have to tap left and right to guide a character up to the stairs to a toilet bowl. If you make one step beyond the top, the poor guy will fall into a pool. One will have you step on cockroaches as they escape from under furniture, and another will put you to fill up ice cream cones of various sizes as fast as possible.
If the challenge proves to be too much, you can always use a "cheat" and skip the level. You buy cheats with real money. So you'd better up your game or pay up.
What I should mention is that hardest Game Ever requires a multi-touch interface. Some levels will be harder if your screen can only detect two taps (a pinch) at a time. That's not to say they're impossible unless, but in this case, you might get frustrated.
I like the concept of getting a different experience with every level, but at the same time, I don't like games that require quick reaction times. I always had the impression that quick-time events and combat games are ruining game controllers, and this feeling still exists even though I'm essentially wiping a plastic screen. Be that as it may, I gather that that most will like playing it.