How to categorise explosions?

hey guys... I want your opinions... how would you categorise explosions?
are they things? or are they concepts?
Is the way something blows up in a game a concept, or is it an additional item...
You aren't collecting any explosions in-game, well maybe in Katamari Damacy... i'd have to check the item list for that...
but the explosions still do exist, even if you aren't collecting them...
but, then again... does this mean for example a bird flying accross in Unreal could potentially be an object?
I'm stuck... i'm not sure how to categorise this...

I personally think we need an entry for EVERYTHING.
achievements are in every 360 game... but are they in every SNES game? are they in every ps3 game?
what if achievements start branching out? Achievements are already in lots of games on Steam now... so that adds more games with achievements...
what if the next nintendo console gets achievements? what if psp games start to get achievements? you have to be able to adapt for change... don't only take what you know and assume that's all that can possibly be...

there are plenty of games without explosions... lots of puzzle games... virtua fighter... Smackdown vs. Raw 2008... just off the top of my head...

this is a DATABASE, not a "oh, let me go ahead and look at what I want to look at" thingy...
the more information you put into a database, as long as it is organised well, the better...