1st thing you should do is pick 3 games/game studio you would like to work at to FOCUS what fundamentals you should work on to get to that level. Use artwork from those games/studios to compare to your work to formulate YOUR learning programme because every artist has varied knowledge/experience. From looking at your work I'm not sure what your focus is as far as being a concept designer because your work is both limited(you need more artworks), and unfocused. While it's fine to draw different things it will slow down you're learning if you stretch yourself out too much. But as a quick start I think you should practice FORM and work on your VALUES. I tried doing a quick example with your 1st piece.

My question would be: which videogames? Pick your favourite ones in your favourite style and say "that's what I want to create." Then try and copy those things you like most and hopefully you'll start to get an idea of where your gaps are: perspective, colour, form, shading, digital tools, etc. I struggle a lot with the same thing in not being able to focus my learning curriculum, because I don't have an end goal that's clear :/ Seeing as you somewhat appear to have that, work backwards from where you want to be and build your curriculum to fill out your skills (while still practicing fundamentals!) to get there. Sorry I can't give specific advise as I'm early down that road too, but I hope this helps still. For specific feedback on your examples here, the thing that stands out most to me is light and shadow. Where's the source light? The tree in the cafe scene has a tiny shadow below it, but the tall pot-plant has a shadow to the left. I'd also think about composition. What's the focus of that scene? The figure in the monolith pic has a dark shadow, but looks to be already standing in dark shadow, yet the monolith has a very light shadow (I think) behind it. In the second last pic, the building on the right is leaning very heavily toward the giant, I'm not sure the perspective should be that severely angled. You certainly have a solid base going and cool ideas :)

Going back to the basics is never something to be ashamed of. Skilled pro artists practice fundamental skills all the time. That said I understand where you are coming from. It can be frustrating to feel like you have plateaued in your training due to lack of focus. This won’t solve your structure issue entirely but when you attempt a more complex painting or project, evaluate its strengths and weaknesses, get feedback from the community, then use that feedback to understand where you need the most practice. That way, you will have a subject to focus on even if you are going back to a basic skill. Aside from that, you can always get structure from taking a course, whether it is online or at a local studio/college. Anyway, keep up the good work. You are well on your way!

Hey there! I'm pretty sure that's because you just don't practice the fundamentals enough. You're not in a hurry ;) Make sure that as you learn, put your newly acquired knowledge to use (i.e. if you are learning perspective, make a painting that heavily relies on perspective, and so on). Keep up the good work! :)

thats strange... i never go back to basics after learnt... maybe this is because you havent done enough practice... or the most stupid thing i did last year was skipping the initial stages and directly jumping... like in a portrait, i should first start with marking proportions, then base color, then slowly structuring it... sometimes this gets boring, but if i skip this steps... my drawing wont result good.... whenever i draw with patience the result is good... and sometimes we have a bad day................