Played the Martin Wallace game The Witches based on Terry Pratchett's Discworld novels with my daughter this morning.
It is a game in which each of 1-4 players is a young witch from the group of Tiffany Aching and those in her age group, that go to Lancre and its surroundings for some on the job training under the eyes of the more senior witches of Lancre and have to solve both easier, more mundane tasks like caring for a sick pig or midwifing a pregnant mother, and hard problems, like the vampires and elves. Tackling the easy problems accumulates the problem tokens, which improves your card hand size, giving you more tools, and smaller victory point awards. Tackling hard problems gives bonuses to the problem solving dice rolls. Cards are played in various ways, with some cards giving some tough choices of how and when to play them.
I like it. It plays smoothly and has a fair amount of flavor built in. I need to reread the rules to see if I missed anything, but played competitively, it felt in this game like it is missing any rebalancing mechanisms. Since you get better at solving things as you succeed and collect VPs, it felt like once I got ahead mostly by being luckier, she was hard put to catch up and I coasted to victory. As far as I could see there wasn't too much to be done tactically in a two, three or four person game to cut into a leader's lead, other than avoiding having tea with them so far as possible or picking off problems that are convenient for them to reach, which are pretty much mutually exclusive strategies. So with the proviso that I may have missed a rule or two which might make a rebalancing house rule unnecessary, here is a possible rebalancing mechanism.
Without going to the trouble of actually keeping exact track of points, it is pretty obvious on the tracks how many green and purple tiles each player has collected. So, after the first turn, at the start of each player's turn, if that player has the most problem tiles, counting purple tiles as two, that player gets an extra cackle tile (or a Black Aliss by the usual mechanism if they also lead in cackle tiles. If the lead in problem tiles is tied, and you are one of the leaders, you get the extra cackle.
Another possibility would be to allow play of some of the cards to take away another player's second move in the turn, which would add a direct competitive mechanism. Would have to look through the deck to decide which cards and how. Maybe any Magic card and you take the hit on cackle to harm the target player, and you play it against them just before the flip to locate the new problem, so you are risking the chance of regretting the decision to hamper them if there is a run of additional crises.
Alternatively, let other players play cards into the active player's problem to raise the difficulty before the first roll, with a Headology being 1 point and a Magic card being 2 points, but costing the cackle token added to the person playing it.
To keep it as a rebalancing mechanism the player(s) with the largest problem token count would not be allowed to play cards against other players.
If the group are all gamers, I'd recommend playing with the fewer crisis tokens advanced variant to make it a bit tenser.
There is also a cooperative two player variant that would not have the problem.