Very few countries without lines within the actual boundaries. China and Brazil almost have some internal clean core. Russia also, but with considerably reduced core, somehow like Spain, and maybe France.

For some "narrow stripped" lands, that’s not that surprising, that lines also overlap so much in the middle, but for some countries with very distant straight lined boundaries, it’s far more astonishing. Some really looks like "drow some random strokes" was the sole instruction.

At least on the easy mode, you're given the names of major cities, coastlines, rivers, and major roads. The city names are also given a gloss in both English and the local script, if the local script is not in Latin.

For a country like China, whose neighboring countries do not use the same language, you can get a reasonably good guess as to its borders simply by drawing in the space between city names written in hanzi and nearby cities without those names.