Oh, so you didn't like Magic and it's creature's general vulnerability. So that made me think of another game, that is very minion centric. Vampire The Masquerade the card game. It pretty much has no cards that directly do something to a 'creature', each creature has to perform the action, which can be blocked. Combat is also entirely card based. Actions are cards. If a vampire doesn't play a card, or piece of equipment attached, it does all of 1 damage. Now, where that comes in handy, is that for you and expansions, you could have new attacks and new blocks and counters, and they could all be usable by existing creatures. A previous set have an attack that is too cheap? You can counter it in the next set by adding a couple of counter cards, or easy blocks.

Jihad :) Yes, early inception of the concept borrowed from this. I actually have never played the game, but I've read the rules a number of times when researching concepts and discussed with a few players as well. Thanks for bringing this up.

(Also, you mentioned percentages, but you don't need to go that route. Fire Vulnerability X could be done as Takes an additional X Damage from fire attacks, or Fire Resistance 1, takes 1 less damage from fire attacks.)

Interesting. What I don't like about 'takes an additionnal X damage', is you could have a fire source that deals 1 damage, but a vulnerability that adds 2 or 3, and it feels a bit odd that with so little fire damage through, you'd get burned so much. I mean, if 3 damage gets through, then I can totally understand 2-3 extra damage. It feels a bit weird, otherwise, it is a good idea though.

Yeah, Jihad/Vampire is a great game full of interesting mechanics that didn't propagate to other card games. We played a ton, some of my friends even did tournaments. One thing that you may notice, is they constantly expanded new powers. Each vampire has a set of powers which dictated which cards they could play, and the expansions would usually add one or two new powers, and new vampires with a mix of old and new powers. There would also be ways one could equip existing vampires with new powers. (Along with a large set of cards that could be played by anyone.) So usually the expansion would add a new power, a bunch of cards for that power, and then expand the old powers with cards to ensure that the new power wasn't overpowered.

For the X, +/-X, you have to be careful, +2 or +3 for vulnerability, depending on how your hit points work, could be overpowering, on the other hand Resistance 3 isn't really that big a deal, even if 3 is the max damage able to be dealt, that just means its immune to fire. Or like you said, you could go percentages or whole multipliers -- takes double damage from fire attacks, takes half damage (round up or down) -- though that can make things quite, well, multiplicative. On the other hand, if something has Weakness Fire, and gets attacked by a mega fire inferno hellblast omega attack for 10, getting annihilated by 20 points of damage isn't that bad.

If there's a mechanism by which creatures can defend one another, it could mitigate old creatures not having special immunity to new damage types, because there's an option for new, relatively immune creatures to defend the old ones. (This mechanic could already be built in, or be introduced in the expansion.)

In a card game, that would probably work best. In a tactical game however, one would assume some measure of proximity. It's a way to somewhat cope with the issue, but I'd still be better off using just new units instead of having to pack all of my units together to insure everyone has 'that' defense.

Yeah, that's why I themed it as "psychic" since it makes the proximity thing less of an issue. Creature X could be "protecting" another specific creature Y just by thinking about them really hard. But even so that's a hassle. It'd be less hassle if it were just a blanket immunity for the whole side: each psychic creature you field gives your whole team an additional 20% psychic immunity, but meanwhile psychic creatures are very vulnerable to physical attacks so you may not want to field 5 of them.

The more general way of stating this "defense" idea is that you can add damage types at will so long as their associated mitigation mechanism doesn't make use of the defense system already printed on the old creatures. In the above, the defense percentage is represented by the number of psychics fielded, rather than a symbol.

(You might not want to do take such routes, of course, because each expansion would take the game further from its original intransitive core. But since these are expansions, that's a decision for long in the future ;)

Other possible mitigations:

• Damage types that have no natural defense but the victim is given a choice that allows them to avoid or mitigate it. (For example, damage that affects the ground under a creature, but is slow enough that they could dodge it left or right. Upon getting hit with the attack, the victim can immediately choose whether to stand their ground (and take the hit) or move. This would be a means of dislodging enemies: it asks the opponent "Do you really want to have that there? Is it worth 25 HP to you?")
• Damage types that harm both caster and target are self-mitigating, even if they have no natural defense. (E.g., "blood magic" in some RPGs.)

Yeah, Jihad/Vampire is a great game full of interesting mechanics that didn't propagate to other card games. We played a ton, some of my friends even did tournaments. One thing that you may notice, is they constantly expanded new powers. Each vampire has a set of powers which dictated which cards they could play, and the expansions would usually add one or two new powers, and new vampires with a mix of old and new powers. There would also be ways one could equip existing vampires with new powers. (Along with a large set of cards that could be played by anyone.) So usually the expansion would add a new power, a bunch of cards for that power, and then expand the old powers with cards to ensure that the new power wasn't overpowered.

I need to get my hands on some cards and an opponent. I found it very hard back then because this game seems like it's dead for the most part (along a significant portion of its community, as would be expected).

For the X, +/-X, you have to be careful, +2 or +3 for vulnerability, depending on how your hit points work, could be overpowering, on the other hand Resistance 3 isn't really that big a deal, even if 3 is the max damage able to be dealt, that just means its immune to fire. Or like you said, you could go percentages or whole multipliers -- takes double damage from fire attacks, takes half damage (round up or down) -- though that can make things quite, well, multiplicative. On the other hand, if something has Weakness Fire, and gets attacked by a mega fire inferno hellblast omega attack for 10, getting annihilated by 20 points of damage isn't that bad.

Indeed. Thanks.

abandon pre-defined types in favor of a more generic damage system

I guess that's what my thread is actually probing for. A reliable 'abstract/generic' system to implement different damage types that has no preconception about units in the game (making previous and new units start on even ground).

or perhaps introduce some default defense rating against as-yet-to-be-defined attack types (such as the dreaded bubble-icous attack )

I could rule that, in the absence of any additional information, all units have 'armor 2' against everything. I do feel this is a cheap and limited solution however.

this is a common design trade off. look at the sims 3, all that stuff, all those objects in all those expansion packs, they all work off of just 6 pre-defined stats (food, sleep, etc).

i think maxis has even played around with what the stats are in the different versions of the game (sims 1 had 8 stats as i recall). but each of those huge game systems (sims 1 though 4) are built around the pre-defined stats.

I'm more and more inclined to stick to my 'original 6' indeed. My current system seems flexible enough to play around with abilities for a while to expand the universe. You could say I'm probably fishing out of water here as this discussion sort of assumes the game would be successful for over a decade, at which point I might run out of ways to keep the game fresh and may need to revisit such core concepts.

My fear comes from what I think is the decay of MTG, how they've resorted to breaking constants about their game (two-sided cards for example).

Yeah, that's why I themed it as "psychic" since it makes the proximity thing less of an issue. Creature X could be "protecting" another specific creature Y just by thinking about them really hard. But even so that's a hassle. It'd be less hassle if it were just a blanket immunity for the whole side: each psychic creature you field gives your whole team an additional 20% psychic immunity, but meanwhile psychic creatures are very vulnerable to physical attacks so you may not want to field 5 of them.

The more general way of stating this "defense" idea is that you can add damage types at will so long as their associated mitigation mechanism doesn't make use of the defense system already printed on the old creatures. In the above, the defense percentage is represented by the number of psychics fielded, rather than a symbol.

(You might not want to do take such routes, of course, because each expansion would take the game further from its original intransitive core. But since these are expansions, that's a decision for long in the future ;)

Other possible mitigations:
Damage types that have no natural defense but the victim is given a choice that allows them to avoid or mitigate it. (For example, damage that affects the ground under a creature, but is slow enough that they could dodge it left or right. Upon getting hit with the attack, the victim can immediately choose whether to stand their ground (and take the hit) or move. This would be a means of dislodging enemies: it asks the opponent "Do you really want to have that there? Is it worth 25 HP to you?")
Damage types that harm both caster and target are self-mitigating, even if they have no natural defense. (E.g., "blood magic" in some RPGs.)

Couple of very interesting mechanics in there. Definitely keeping your vision of psychic units in mind in case that could be used. I had a team of Spirits that were mechanically weak and this might supplement them well. Thanks!

Total aside, but Vampire/Jyhad plays best with around four players, as then the table mechanics come into play. You can only intercept or attack the people to your left or right, and you only get rewarded for killing your opponent to your left (or was it right), basically, in one direction, you have your prey, and in another you have your predator. And then you have to worry about the players you can't reach, calling votes and doing other shenanigans that can affect you indirectly.

And yeah, it's probably deader than a doornail, so good luck finding four players =)

Total aside, but Vampire/Jyhad plays best with around four players, as then the table mechanics come into play. You can only intercept or attack the people to your left or right, and you only get rewarded for killing your opponent to your left (or was it right), basically, in one direction, you have your prey, and in another you have your predator. And then you have to worry about the players you can't reach, calling votes and doing other shenanigans that can affect you indirectly.

A short while before giving up on Magic, I actually inserted this house rule for 3 player games to avoid the constant 2v1 shifts that weren't so fun. It was fun too, it's one of the things I really liked about Jyhad.