Idratex

If by types of entities you mean the equivalent of classes eg in which they have the same properties but with different values of these properties, then not a lot. Although it would be nice to be able to add weird and wonderful new entity types I only really need the two mentioned (Program and Item) for now.  I don't want to use an entity system for its own sake; I'm considering using it because it's the Next Big Thing and I can see why it is superior, in many respects, to huge class hierarchies. However the class hierarchy isn't very deep here; as mentioned, different entities are not defined as much by a different class as they are by the data values they have.

And yes, components would let me define new entities outside of the program itself which would be nice. I suppose it would benefit me in the long run when compile times grow extremely long.

Going ahead with my inheritance heavy approach still feels wrong to me, but components also seem overkill ._.

But what I want to avoid this time round is doing a U-turn and starting from scratch... again. I seem to keep doing this but it obviously doesn't help, which means I have to choose a way of doing this and stick with it.

I didn't mean to suggest that the two concepts are mutually exclusive - having a prototype-based component system did cross my mind - but I wasn't sure if it would be worth it. I suppose it all depends on how specific my intentions are. Funny how you talk about Flyweight, I was just reading that as thinking about all this sharing of data reminded me of it! Thanks for those ideas though, I think it may be the fact that doing something slightly different that isn't spelled out for me just feels weird which keeps me from seriously considering things like that.

One reason I like components is that they lend naturally to data-driven design, rather than having everything hard-coded in. But again I'm wondering if it's really necessary for a project like this. It's not like I'm straight out of the C++ tutorials and have just learned about a fancy new way of doing things either - I've read quite a bit on the subject, but unfortunately that seems to be all I ever do :S

Anyway, I'll see how it goes. Thanks again for the advice.