I 've got an ancient PC with: Intel Pentium G620; 3 gbs of RAM; Intel HD Graphic Family 512 Mbs; 32-bit operating system. Can i upgrade this piece of trash into a PC which is able to play Eternal Crusade? Attention: THIS IS NOT A JOKE
Uhh Do you want to keep your current rig or buy a new one to upgrade? I don't know if you're asking for help selecting a new PC or want help looking for components
he's asking if it would be physically possible to upgrade his box, honestly it really depends on your case, if it's a slimline, good luck. But if it's a big tower you can basically gut it and install new hardware.
Wellz you'z wuld 'ave ta mor or less rip da bitz dat makez it jus a Shootah, and strap on da bitz dat wuld make it a Big Shootah. 'Ow well dat turnz out dependz on da Mek rippin yur Shootah apart 'Ow much teef at ya willing ta spend an wut sortah flash'ee bitz do you wantz on it?
Take no offense mate, but it looks more like you're trying to upgrade a shoota into a reaper autocannon. DISCLAIMER: I'm no expert, so take this with a grain of salt. First of all, the CPU. Pentium is a very low-end processor now, and I'm not sure if you'll be able to upgrade to at least an i3 processor without changing the motherboard, because the CPU slot (sorry if that's not the correct term) may very well be different. And that's if you want to remain in the Intel family, if you want to switch to AMD you're FORCED to change the MoBo also. That alone would be like buying a brand new rig. Then, you'll have to buy a GPU, because the Intel Graphic is either an integrated GPU, or it is very crappy (512MB are very few today, and surely don't meet the minimum specs required for EC). You'd have to buy at least 1 GB of RAM too. Here you can find the minimum specs. Honestly, you'd probably be better off buying a brand new PC, you'll have much more flexibility without spending too much more.
It would be slightly cheaper to replace parts, but yeah if you're not tech savvy or know someone who is, it would be wiser to buy a new rig.