We are open to seeing suggestions about various run formats that may or may not be present. One of the considerations that we have to take into account is how active such a category will be. If you are interested in trying to get a new category going, you can post a thread about the category indicating its a proposed category with an initial run under that categories rules and see if it drums up any interest. If it generates sufficient interest, the category may be added as an official category. The official categories that are currently listed on the website are those categories that are currently used or have been used relatively recently ( post 3.8 ) in community organized races. Otherwise, they are official categories because there are a fair number of runs submitted for them (Brutus Rush for example).
Ruthless? Maybe yes its random because of support drops - but can be fixed by rules /almost no uniques at all - pure mechanical skill from player and skill gem revelation.