When comparing Monsters & Magic vs Heroes Against Darkness, the Slant community recommends Heroes Against Darkness for most people. In the question“What are the best tabletop RPGs?” Heroes Against Darkness is ranked 33rd while Monsters & Magic is ranked 42nd. The most important reason people chose Heroes Against Darkness is:
The game uses a single "d20 + modifier ≥ target" mechanic for everything. Characters can be created in less than 5 minutes. The writing is concise and clear.
Ranked in these QuestionsQuestion Ranking
Pros
Pro The Effect Engine
The game uses a single core mechanic, which is flexible enough to cover a wide variety of situations. This helps GMs immensely when characters want to do things that aren't already covered in the system.
The mechanic itself works thusly: all rolls are 3d6 + modifiers minus difficulty. The result is how many effect points the player can apply to the action -- or, if negative, how many consequence points their opponent can apply to a reaction. Dealing damage is one use of effect points, but there's a limit on how much can be dealt at once, so additional effects (e.g. distracting, disarming, unmounting, etc.) see constant play instead of only being used rarely or by super-specialists. This also means failure is interesting, since it results in consequences!
This mechanic is used to do everything, and the game essentially consists of nothing but examples of how to use it.
Pro Interesting combat
Attacks generate effect points, which you spend to do things to your opponent. However, the amount of damage you can do is limited, which forces players to do other things... and the effect system is broad enough that these can be things like cutting off a carrion crawler's tentacles, knocking an opponent's sword out of their hand, and so on. Failures on attack generate consequence points as well, which your opponent can use to do things to you.
Pro Mental defense and hit points
Characters have a "Mental Defense" score and "Mental Hit Points". These are used to help provide a unified system for handling social encounters and mental attacks via magic.
Pro Focuses on simplicity
The game uses a single "d20 + modifier ≥ target" mechanic for everything. Characters can be created in less than 5 minutes. The writing is concise and clear.
Pro Deep, without being cluttered
A lot of meta-tools such as templates, etc, that make combat encounters incredibly simple to construct. Great tools for creature-building. A lot of good information on world-building. You can make any type of game efficiently, from hack-and-slash to role-playing. If you have played in a D&D campaign, this is a great choice for your first outing as a GM.
Cons
Con Not currently available in print
Is only available in PDF.
Con Few monsters & spells provided
The included rules have only about 20 monsters and 1st and 2nd-level spells. Third party publishers have supplements that provide more, or you can use ones from old D&D.
Con Requries prior knowledge of RPGs to completely understand
Some knowledge will be required to understand the rules as there are some unexplained conventions that are presumed to be understood.