If you are member just login, go to the game page, hit the "edit this page" link and then scroll to the bottom of the current images where it says "You may upload more than one screenshot." and hit the"add another item" button.

600 dpi is somewhat overkill for images that will generally be viewed online only. I suggest as a guideline scanning at 150 to 240 dpi for screen display - that is they will look fine on screen and DL quickly for viewing online (on folks PC's that have slower internet speeds).

Scanned box art is always appreciated tho' and replacing that blurry box art pic on that page won't be a problem.

However, if uploading pics, respect the screenshots of game-play etc, that others may have uploaded. Leave them as is, please, else it may upset those who have spent the time taking the screenshots and uploading in the 1st place.

In "Edit this page" mode, remove the blurry box art pic & add your pics below the screenshots that are there. Thanks.

600dpi is unnecessary overkill for most things.

150dpi is good enough for home / desktop printing at full size. 72 or 100dpi is more than enough for on-screen use at full size ... at least on a "normal" screen (those with Retina / 4K displays might prefer slightly more).