recently I developed few games for mobile devices in the style of the Ketchapp games:
- Simple premise, maximal fun.
Just like those games, I took most of unnecessary things out so the games were stripped to basics.
With basics I mean the games was about avoiding to fall a platform like ZigZag.
However, my games end up pretty boring, despite having sweet graphics.

The quality of the graphics has no bearing on the game's fun. Games should look good, but graphics are not involved in fun. The graphics can have an impact on engagement, though; if the game's character is endearing, and looks scared of falling, or looks terrified when falling, that helps the player want to keep the character from falling. The player becomes more engaged - more inclined to play.

Im not sure what factors I need to take into account to make the game simple but addictive,

So you say the heart of the fun is "not letting the character fall." Take a look at Limbo. In Limbo, the goal is to not let the character fall, but not only that. The character also shouldn't be crushed by falling objects, or impaled by monster horns. And the character needs to get through the game world to the other end.

If your game is only about not falling, that can still work, provided that there's another goal of some kind. One way to not fall is to stand in one place, but that is boring. There needs to be a primary goal, and "don't fall" is only the secondary goal.

In order for a game to be more than just a "patience level indicator," the difficulty needs to ramp up slowly. The difficulty can be presented in interesting ways. There can be places where the character is safe from falling while remaining stationary, and there can be places where the character mustn't stand still because falling is inevitable over time. There can be enemies of varying types, who act in ways the game mechanic provides defenses against. Then the enemies and the places can be compounded in challenging but overcomable ways. (Spellcheck flagged "overcomable" but that should be a perfectly cromulent word for game designers.)

Am I making sense?

I know that the question is a bit broad, and the topic my not be in the right forums

It's in the Game Design forum. That's absolutely the right forum for this question.

Just from looking at the images I would say ZigZag looks more interesting than yours. Perhaps it's the car, I have nothing to back this up but I would guess that limits the audience too (though that wouldn't necessarily make your game boring) where as the style of ZigZag looks to have more general appeal. The collecting diamonds looks like it helps too. Perhaps you have distilled it too much.

Who says it's boring? You, friends? I think it's quite hard to say why some of these games become insanely popular and others don't. Expectations influence our future experiences and looking at ZigZag's screenshots they do look more appealing (and thus I would expect to enjoy it more) than your screenshots.

Why not make it look more fun? Maybe make it look like a toy card on a cartoonish track. Maybe have a pursuer (police car) which is constantly gaining on your car and have simple speed boosts scattered around that driving over helps you maintain your lead. Hopefully that would add a little excitement.

Thanks for the answer.

Who says it boring? Im saying that...any the low download numbers :-)

Again, this helped me a lot.

Mirza

Low download numbers don't necessarily mean it's boring, it's just undiscovered. It'll probably take quite some time before someone takes the time to comment on your game and confirm if it's boring or not.

>> I took most of unnecessary things out so the games were stripped to basics.

less is not always more.

>> However, my games end up pretty boring, despite having sweet graphics.

not as sweet as zigzag. (personal opinion)

>> Why do all my simple games end up being boring?

perhaps because they are too simple?

>> Why is my game, the upper one, so boring?

hard to say without playing both games, but it appears to be simpler - perhaps too simple.

>> Who says it boring? Im saying that...any the low download numbers :-)

i'd say they have a better name and the game looks like more fun based just on the screenshots, that could account in part for your download numbers, with the rest accountable to lack of time since release of your title (IE undiscovered as Nanoha says), and lack of marketing on your part.

never try to go head to head with the competition until you have the superior product. you'll just lose. that's a basic rule of thumb in any business.