If I play solo, I usually play with four investigators.
I play with one big box and one small box expansion.
I determine randomly if there´s a Herald, Guardian, Institution, Relationship or a personal story by rolling a d8. On a 7 or 8, the element I rolled for comes into play.
Silver Twilight Lodge: I use a houserule to make being a member of the Twilight Lodge more attractive. If you become a member, you place two clue tokens on the membership card. If you gain a clue token due to an encounter in the Inner Sanctum, you´ll get one of these clue tokens from the card in addition. You can only do this twice per membership card and you have to leave the location and come back before you can do this the second time.
Gate Bursts: I hate Gate Bursts! I think they are an extremly frustrating element of the game and can really kill the fun. You simply draw the wrong card and all your hard work is lost. F****!!
So I decided to give players a chance to react and prevent these bursts from happening: If a Mythos card shows a Gate Burst, you place two markers (i.e. these visited other world markers that show the backside of the gate cards) on that location. At the beginning of the next two mythos phases you remove one marker. If there´s no marker left (after two turns) the Gate Burst will occur. Until then, players have time to prevent it by moving to that location, making a Lore or Strength test -1 and spending 3 clue tokens. They do this after they had an encounter there.
New unstable locations: I found this variant somewhere on BGG, but it has been seemingly removed, so I don´t know whom to give the credits for…
1. During setup choose in random two different rift progress markers, then shuffle them back into the pile.
2. The locations depicted on the chosen markers will be the unstable locations in Kingsport for the current session.
3. Mark the unstable locations for easy reference with any tokens you’re not using(say, the brood tokens).
4. Place clue tokens at these locations.
5. Each time a rift progress marker depicting one of those locations is placed on the rift track, open a gate at that location, place a monster there and place a clue token at a location depicted on the immediately adjacent rift marker(that shares the same movement pattern, or if not applicable,at another locatiion depicted on rift markers that are part of the same rift track. If there are two such locations, place a clue token on each).If there are no adjacent markers on the rift track, no clues appear.
6. If a rift marker is placed that depicts a location that has an open gate already, a new monster is spawned there.
7. Monster surges in Arkham only affect the base board.
8.Gates in Kingsport don’t count against the gate limit(maximum number of gates open), nor do they advance the doom track upon opening.
9.Gates in Kingsport cannot be sealed, only closed.
10. Once a gate in Kingsport is closed, the gate location becomes stable and no gates can appear at the location for the rest of the game.
11. Each time an investigator closes a gate at a location in Kingsport, he gains a clue token, and all associated rift markers depicting said location are removed from all rift tracks.(or placed face down in case of an active rift)
12. When the Ancient One awakens, for each open gate in Kingsport one extra success is required to remove a doom token in final battle.
Moving to the Strange House on the hill: Moving to these special locations costs 2 movement points instead of a whole turn. You’re not allowed to use any vehicles. It´s still hard to get to the house, but at least we might see someone try now. In addition you´ll get an extra skill and, once in the remaining game, you´re allowed to cancel any one card (also drawn by other investigators)!
The Captain of the White Ship: When the player gains this card, he also gains a skill. In addition, from now on, it only takes him four clues (Hastur 7) to seal a gate.
Black Goat of the Woods: To make the membership in the “One of the Thousand” cult more attractive, a player gains two clue tokens when he becomes a member.