I think one of the major appeals of the GLOG is the rules for spellcasting. Spellcasters know a certain number of spells and possess a certain number of Magic Dice, or MD. Whenever you cast a spell, you choose how many MD to invest in it. The spells all have variable effects. If you roll 1-3 you get the MD back to use again, 4-6 it's used up for the day. If you use two or more MD and roll doubles, something bad happens. If you use three or more MD and roll triples, something really bad happens.
Goblin Punch laid out the original rules for spellcasting. Coins and Scrolls rewrote them. Since then others have made tweaks here and there, but the basics haven't changed much.
(The relative popularity of the magic rules from the GLOG, DCC, and Wonder & Wickedness suggests something like a general theory of what some players want from magic in their roleplaying games - spells that can be cast more than once each day, unpredictable magical outcomes, the ability to invest extra resources in a spell to hopefully make it stronger, and a small risk of catastrophic failure that makes the decision to use magic inherently dangerous.)
Most GLOG spells have variable spell effects that depend on the number of Magic Dice spent to cast the spell, which is noted as [dice] in the spell description, or on the number you get by adding up the result of all the MD used in the casting, which is noted as [sum].
Notably, almost all GLOG rulesets allow casters a maximum of 4 Magic Dice, so the [dice] variable will range from 1-4, and the [sum] variable from 1-24.
A few have effects that simply get stronger the more dice you used to cast them, but not in a strictly numerical fashion. The most common examples are spells where the duration of the effect increases (such as from 1 round, to 1 turn, to 1 day, to 1 week) or where the size of the possible target increases (such as from human-sized, to horse-sized, to house-sized, to castle-sized).
It's also pretty easy to imagine spells that either create objects or manipulate them, where the number of MD determines either the material the objects are made of or the technological complexity of their construction.
|from Little Witch Academia|
I had a couple ideas for other ways to produce variable spell effects. Let's call them Dice Placement Spells and Random Effect Spells. Both would likely use a new variable we could call [number], which indicates the result showing on a specific MD. (Remember that fun mnemonic they taught you in Wizard School? "When dice equals one, number is sum!")
Dice Placement Spells are the more cerebral and gamey of the two. They have 4 possible spell effects, and you choose which effects will take place by assigning an MD to each one. If you use 1 MD to cast the spell, you get one effect; use 4 MD, get all four.
That's not that many decisions to make, but the thing that would turn this from a simple spell to a puzzle is if the different effects care about the [number] on their MD, particularly if different effects "care" in different ways. You'll probably want to be a little careful here to avoid inducing analysis paralysis on your players.
You could have effects that grant a +[number] bonus, effects that impose a -[number] penalty, effects that only work if [number] is equal to the target's HD, effects that always work but work better if [number] is equal to the target's HD, effects that expand the spell out to [number] additional targets or lengthen the spell to [number] additional rounds or turns. You could create an ongoing effect, where each round, something small happens based on [number], and then you subtract 1 from it until it reaches 0. You could create a countdown where each round, you subtract 1 from [number] and when it reaches 0 something big happens.
Random Effect Spells are more unpredictable and swingy. They have 6 possible spell effects, and you don't get to choose which ones will take place - instead, the [number] on each MD will tell you which effects you get. There are no choices to be made, just beautiful chaos.
Since the [number] of each MD determines which effect it activates, you can't use [number] as a variable in the spell's effect. You can set up interesting combos where one effect makes another more powerful. In a "dice placement spell" that would likely just result in the player choosing the combo every time, defeating the purpose of offering a choice - but in a "random effect spell" the combo can only happen by chance, making it more like a pleasant surprise when it turns up. Also, remember that doubles and triples cause spell failure, so for any successful spellcasting, each [number] will be different. It doesn't really matter what order you put the effects in, but the spirit of GLOG spellcasting suggests that the weaker effects should correspond to lower [numbers].
One final consideration with both these new templates is that because they produce spells with multiple effects, it would be easy to accidentally make them much more powerful than other GLOG spells. Individually, each effect should probably be weaker than a typical spell, so that when multiple effects happen at the same time, they add up to about normal.