Well, I put everything in the title but I can slightly expand here:
Could you help me with that? Thank you! 
reverse pacman where you micromanage the ghosts and try to trap an AI!
On the contrary, while you’re practicing, it’s better to build simple, already existing games. Like tetris-clone, match3, platformer, simple 3D FPS shooter, etc. Don’t worry about the graphics, use grey-box or something already done stuff. There is a ton of free stuff to use on the internet (usually non-commercial use, but sometimes even commercially).
Then when you’re done, start to modify them, try to find new ways to use the same idea, mix it and match it. Try to find what you can add to these simple games.
And when you finished a couple of these, you will have some experience AND you practiced both design and coding.
IMHO
Hi! I deleted some posts that were either elitist or just not adding anything. I think you should try something that inspires you. It does not need to be a game, perhaps a lady walking along in the moonlight solving puzzles? side scroller…
I have tons of ideas for totally original games that have definitely never been done before:
Flappy Pipes: you play as an infinite succession of vertical pipes with gaps in them that can also flap up and down. There is a bird flying in a straight line and you have to flap the pipes so that the bird always flys through the gap.
Unpac Man: you play as a little purple circle guy who has to leave dots all over a maze and eat all of the ghosts that you come across. If you accidentally touch one of the power-downs, the ghosts start to chase you for a short time and you have to avoid them.
Not-at-all Slender Man: You have to collect 8 pages in a brightly-lit forest. While you collect the pages you have to stay close to this short, over-weight guy who’s not scary at all. If you get to far way from him you lose.
Edit: also see Game Ideas! Post them here.
With such awesome suggestions as the 3 people above gave its hard to add much.
I guess I would just suggest kind of along the lines of what has been said… maybe take a tiny game (retro are good inspirations) and reimagine it with your personal experiences / likes / hobbies etc.
Something that styles the game to you. Maybe that is Pac-Man but actually a mom trying to get her 4 kids in line or whatever. I have no idea what your life experiences are or what your hobbies & interests are but maybe look there for inspiration.
And I think that is also the heart of what can make a game that not only has a lot of meaning to you but also can connect with a lot of others. Alright that’s all I got. Good luck though!
That’s always a fun one.
https://www.kongregate.com/games/boredmormon/revenge-of-the-ghosts
It was years ago, I have no idea if the link still works.
VR survival shooter with crafting elements.
Hi and thank you everyone for your ideas. I actually need to read ideas from others, not only for training myself at how to make them but also to train myself to have ideas. No matter what I do, I seem to be unable to have ideas… and if I have one by chance, I’ll reject it after a while, lose interest. 
You could always take to games that don’t match up and merge them in to one. Like take pac man and asteroids. Then find a way to make it work.
Christmas coming, it’s not too early for you planned and design something which relate to it, character can be Santa or … Deer it depends …
Or the turkey… :giggling:
How about a cow on a snowboard where you need to take a few bumps with the right angle in order to build momentum before attempting to leap across a ravine to clear the level. You could name it Moomentum.
Oh! A maze game where people say sexist stuff and you have to get over to them and punch them in the nuts before the voice bubbles fade away.
Anything using a 2D grid, like M[ ][ ], is good for practicing array use and nested loops. Even those matching games. An old trick is, say you want a 10x10 grid. Make it 14x14 and only use the middle 10x10. That way you don’t need to worry about off-ends (make the surrounding 2 squares all wall or all blank, depending on the type of game).