You might be confusing indie games with game jam games. Most of the games I have published on my site are from game jams I have attended where you get less than 48 hours to make a game (lately I've even been doing 1 hour jams), it's hard to make a game complete in that time frame even when multiple people are involved. So you should think of these games more like a prototype or proof of concept than actual games :)
They are good starting points to make actual indie games.
I also love the concept of a gta game in antic Athens, I hope we get to see something like it one day!