I have roughly 3 Cube Towers (6 cubes tall) shelving of RPG books in our tiny study. Another three feet of board games are on top of those. There is also a foot or so of card and envelope stored games in a bookcase nearby (nearly all the original run of Cheap Ass Games share a basket storage in that shelf, along with things like FLuxx, etc that are basically just one card box in size filling out that shelf). The Books and boxed games are all spine facing out, organized by system (so all the CoC stuff together, all the GURPS, etc)

Game supplies are mostly stored in an 'under the bed' box beneath our living room Futon couch (this is stuff that is primarily for rpgs that get reused at various times).

Banker storage file boxes (clear plastic) are used for what is older and doesn't fit in all that. One in the upstairs storeroom, and 5 are down in our basement storage space. These are about 18" long and one full sized RPG book wide. We have one for old board games, and the rest are much older roleplaying games (1990s stuff mostly, but also 1st & 2nd ed D&D materials). These each have an inventory sheet showing forward for quick knowing what is in what.

Everything else is pretty much in electronic form... about 30 GIG of files, mostly PDFs but some as Word Docs, stored on my laptops and my Google Storage.

All of this was after a purge some 8 years ago when our housemate moved out, since we had to go thru stuff and separate out what was "hers" which went with her (this removed some duplicate RPGs and some board games we had no interest in), and we got rid of some things that we decided none of us had interest in holding on to (demo copies and items that we got for review back when we ran our APA and a few 'prize' items that she'd won at conventions but had no interest in etc).

We've reduced the number of physical copies of games we buy considerably since the purge (since my eyesight has become impaired) so since then only 1 or 2 shelf copies of game books have been added each year and may 3 or 4 card games I got to play with my client when I was working as a PCA. I haven't bought anything that was non-electronic in almost two years now, since we reduced our cash spending footprint to save up for my surgery earlier this year etc.