kakuzukyo: you must have had your flash storage full. Right-click on flash screen and click settings, therein you find Local Storage tab and drag the bar to Unlimited.
kobepascualXXX: you use runes by forging them on a weapon. Moreover, you may upgrade a weapon while taking a risk of breaking it. It gets stronger and stronger but the maximum upgrade limit is 10.
tyj1995: the more of them there are, the slower your computer would run -- having it limited will prevent the chances of some people's computer and/or the internet browser from being frozen.
 "Whiteboard Tower Defense"){kind=icon}
 "Hover Bot Arena"){kind=icon}
 "Feudalism II"){kind=icon}
 "Hanna in a Choppa"){kind=icon}
 "Ragdoll Avalanche 2"){kind=icon}
 "Storm the House 3"){kind=icon}
 "Frantic"){kind=icon}
 "Meat Boy"){kind=icon}
 "270: White House Tower Defense"){kind=icon}
 "Bloons Tower Defense 3"){kind=icon}
 "Microbe Kombat"){kind=icon}
 "Escape from really boring island 3"){kind=icon}
 "Ether War"){kind=icon}