A few initial thoughts - warning this is based on US market/sales frequency/pricing, I know stuff is higher priced/harder to find sales for you guys across the pond so take it with a grain of salt:
Wow to me that's a big % for the case for a "budget" build. You might consider going *down* the scale on this. I personally don't care what my pc looks like, I just want a solid reasonably quiet case - if it was me I'd shop around for better options, and ESPECIALLY look for cases on sale, I have gotten awesome cases for $40-50 delivered and decent cases for even less. Be aware of shipping costs on cases, it's usually better to find a place with free/fixed price shipping and get the case from there even though the list price might be a bit higher. If you have the time, it's worth looking around in local shops to see if you can find something decent on sale and avoid the shipping cost. Do check reviews sure the case is big enough to fit the full sized gpu and cpu cooler (the R9-270X is basically a 7950 right? Those are LONG. And the Hyper 212 is pretty tall. I'd assume the ones listed on Logical Increments are big enough to handle them, it would be a good idea to make sure, especially if you consider other cases). Apply the savings to cpu/gpu.
For gaming, look really really hard at the equivalent or slightly better Intel set up. The AMD 6350 has 8 cores, and gaming performance is STILL mainly 1-2 cores, although this has begun to change. So I would try to find a super hot deal on something like a i5-4670k + z87 motherboard, or maybe an i5-3550P or 3570K if the 4670K is too pricey. Try to find benchmarks for the most demanding games you want to run at the resolution you want (I guess 1920x1080 for that monitor) to see which cpus have acceptable performance and best bang-for-the-buck. Actually looking at a few comparisons that AMD 6350 competes pretty well, still if it was gonna be my gaming system I'd be looking hard at Intel.
Are you gonna overclock, and are you gonna try to OC a lot? If not, or if you just want light OC try starting out with just the stock coolers, save that 28 Euros and apply it to get a better base cpu. I've always been able to do moderate OC with the stock coolers and then you can take some time to wait for a killer sale on the add-on cooler (like I can usually get the Hyper212 Plus for $20 or so, several times a year). If you're dying to do heavy OC right off the bat, yeah might as well get the cooler now, and don't forget good thermal paste (I usually settle for Arctic Silver 5 but I'm not an OC maniac, search all the reviews if you want to try to cut a few degrees).
GPU - looks reasonable, but you might have trouble finding an AMD GPU in stock at a decent price because of cryptocoin mining - be ready to look for the equivalent or slightly better Nvidia card, you'll probably have better luck.
If you're a student, look for student prices for Windows, you can probably get it for 30%+ off the 73€, apply the savings to cpu/gpu. Especially if you have any kind of old windows license you can use as a base to get the "upgrade" version instead, if you don't mind the slight hassle of doing it that way.
Good choice for PSU, I like Seasonic.
General shopping tip - If you've got the time, look at combos 1-2 even 3 steps above what you're aiming for and price those out too, looking for hot deals - a LOT of the time you can hit a hot sale and score a more powerful combo for less than you'd pay for non-sale lower performing gear.
Basically your core parts are a pretty solid combo, all I have is the above minor notes/suggestions - good luck!