Thinking about something along the lines of
150 unique enemies
20 boss monsters to fight
30+ tilesets and probably 500 unique rooms to explore
200+ unique items that have different functions that do not simply increase a stat by +2.
A puzzle system with probably about 50 unique elements that can be mixed around and connected to each other.
A game that big I'd say start off with an aim for/promise of Windows PC only, especially if you're using NW.js to wrap it into an EXE/executable. Our Kickstarter backers took it pretty hard when the game turned out not to run on Linux, Mac, and etc. like we hoped it would.
Our game stopped working properly on Linux and Mac (think Mac is broken for all with NW.js right now?) by the time it was 300MB in size ( http://store.steampowered.com/app/334190/ ), even though most of the size was music (full 8bit and 16bit soundtrack).
We've switched to another engine for future games, but that's mostly for non-Windows export options, not just because performance on Windows alone (another tip would be try to minimize CPU usage as it really breaks the platforming behaviour once some jank gets in there, but that might be better with the newest version of NW.js).
Other than that, yeah C2 can do some pretty cool stuff <img src="{SMILIES_PATH}/icon_cool.gif" alt="8-)" title="Cool">