Goals: There’s a ton of current games that I’d like to try, less for graphics, mainly for story (my most played game is probably Dwarf Fortress), and also pretty much anything going back to even 2011. So I guess the goal would be to be able to play current titles like Fallout 4, XCOM 2, etc. on mid settings in 1080p. I’ll also need some computing power for Matlab stuff in the near future (math student with master thesis coming up here), so a good CPU would be nice, what with Matlab supporting multiple threads fairly well. Everything else should be covered in the rationale below.

Budget: I can live with where I am now, considering I’ll still need to get a monitor, which is likely to end up being some €100 thing. I guess I could justify going up to €750, mainly if there’s a better/more stable HD out there.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-4590 3.3GHz Quad-Core Processor (€201.90 @ Caseking)
Motherboard: ASRock H97M Anniversary Micro ATX LGA1150 Motherboard (€75.89 @ Amazon Deutschland)
Memory: Kingston HyperX Fury Blue 8GB (2 x 4GB) DDR3-1600 Memory (€44.36 @ Amazon Deutschland)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (€51.45 @ Amazon Deutschland)
Video Card: MSI Radeon R9 380 2GB Video Card (€209.90 @ Amazon Deutschland)
Case: Cooler Master N200 MicroATX Mid Tower Case (€51.89 @ Amazon Deutschland)
Power Supply: be quiet! 530W 80+ Bronze Certified Semi-Modular ATX Power Supply (€79.90 @ Amazon Deutschland)
Total: €715.29
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-12-20 13:14 CET+0100

Rationale for part choices:
4590: As said above, I’d like a reasonably powerful CPU, and by the time I’ll upgrade the CPU, I’ll probably also need to replace the motherboard and RAM for socket reasons, so the 4590 seemed like a sensible choice. Matlab and other computation software is also multithreaded pretty well, so the quad-core makes sense.

Mobo: I can’t really make an informed decision on this one. As far as I can tell, the benefits of higher end motherboards are overclocking capabilities (which I don’t want to do), more PCIe slots (although any board should support what I’m going to use) and support for stuff like DDR4 RAM (which would be nice to have, but not enough of a priority to spend a lot of money now instead of upgrading later). Is there any reason I shouldn’t just get the cheapest µATX board I can get?

RAM: 8GB seems like enough, and the manufacturer appears to be popular in this thread and elsewhere.

HD: I’ve been reading about WD drive failures being a common thing, but I don’t really know which manufacturer makes good drives in that price range. So ???

380: As far as current games go, this seems like the sweet spot where you get good performance with only slight limitations as far as setting go, if you’re not on 1440p or higher. The 380X isn’t available in Germany yet as far as I can tell, but ultimately I probably wouldn’t be able to justify the higher price point anyway.

Case: Seeing as this is my first build, getting something that’s easy to build in should be a priority, and from the things I read this is the case with this case. Otherwise, I can’t really tell what makes one case better than another, so there’s probably a cheaper alternative out there that’s just as good.

PSU: Again, this being my first build made me reach for a semi-modular PSU, and the wattage should be enough for any future upgrades. The brand seems to have a fairly good reputation, so that’s basically what I went off of.

Upgrade path: I’m fairly confident this rig should be capable of running newer titles for the next ~1.5 years, by which time I might look into upgrading the GPU and at some point the CPU+mobo+RAM. I’ll think about that when I’m unhappy with the performance I get though.