Isn't Against the Darkmaster supposed to basically be the same game with the Tolkien stuff scrubbed off?
Not even scrubbed off; just given a fresh coat of paint. there are some mechanical changes, fairly minor.
It is not a clone of MERP, but more a spiritual successor. And awesome.
It's a clone, but it's not a strict retroclone, in that category of clones like DCC... the core is the same, the setting the same as far as mechanics go, but there are single edition level difference. I use Pseudoclone (a term I heard from others in the early 00's) for such.
Hell, it even clones the trade dress of MERP!!!
It doesn't keep the percentile values of the attributes - since MERP doesn't have the current/potential split of RM, the percentiles are there in MERP as vestige of RM. Going straight to the modifier value is a simplification. It uses the same method of each class has DP specified for each skill area, can transfer DP at 2:1, and how they're set is by class.
It has the same system of critical hits, but using names (Superficial, Light, Moderate, Greivous, and Lethal) instead of letters (A-E).
the General Resolution Table is slightly modified (75-99 instead of 74-90, and adjusting the adjacent).
It's far closer than a spiritual successor typically would be.