I wanna build a web game like : Cookie clicker . But I just learnt basic html/css. What am i need learn?

JavaScript.

1 line cookie clicker:

(x=>(x.body.innerHTML='')|x.body.appendChild(Object.assign(x.createElement('a'),{text:'🍪 clicks: 0',onclick:({target:t})=>t.text=t.text.replace(/\d+/,x=>+x+1)})))(document)

Probably Javascript. I had a class that did some small games using JavaScript and P5 that culminated in an underwhelming pinball game. Alternatively if you want to start with a ready made engine Godot is fun to work with, too. If it's a simple clicker game though, I think something more lightweight like js would be easier to work with, as you can focus on the language and not get caught up in the editor. P5 has a live editor as well, which is great for toying around with new ideas.

You need to learn a bit of javascript, especially tracking the mouse click events and incremental functions for scoring and rewards. I made a project cpstest.pro that simply counts clicks and calculates click speed. You can go there and view source code to understand the working. I hope it'll help you with your cookie clicker.

Two way to do something like this:

• A Game Engine (more heavy, less difficult, in example: Godot Engine -> web export)
• JS and animation library (most light, most difficult)