This exact setup happens all the time in movies, so let's examine how they handle it.
If they are the only character, then as a GM, completely tune the story to them. They shouldn't have to do hacking, or at best they have to shoot their way in to where the Russian hacker who already knows stuff is. James Bond doesn't use keyboards. Avoid his minimums except for once in a while for dramatic effect, or to introduce Bond Girls who have that skill set. As for addressing his strength - he's an expert shooter, but is always having to go places where he doesn't have a gun, or just has a pistol when others have machine guns, or has a machine gun when they have tanks. Or places where you can't just shoot the heck out of everyone (like a public casino) without having long term consequences.
If they are not the only character, the other characters are in danger. What do The Killer and Hard Boiled have in common? Lots of OTHER people who get killed. The chick who's along that's in danger. Or your buddy movies with one killer type and one intellectual (or even just not a killer, take Rush Hour) - the killer has to spend a lot of their time protecting/coaching/handling the less combat oriented person. One of the big risks of having a min-maxed PC in the group is the min-maxed bad guys the GM has to toss on, who can often terminate the non min-maxed PCs in a round. It becomes the combat monster PC's job to avoid that, or else the whole party dies and they say "new game, and be less of a goon this time please."
This is of course advice for in-play. You should try to head this off ahead of time by disallowing (GM)/forgoing (player) total min-maxing by choice of system or GM guidance. Because as you note it ends up being unsatisfying even in your maxed area.
I have tried this in two ways in the past. I think of the two, only one will be of use for your objective.
PC Villain in the Group
Create the villain with its player and discuss what their villainous goal actually is. Ensure the player can and will commit to being a villain. Their goal should require the villain to need to be close to or involved with the players to achieve. You will probably want the nature of your villain to be a big revelation at some stage of the campaign, so they need strong hooks to tie them to the heroes, and to tie them to what the heroes are trying to do.
Of course, the heroes will want to achieve a positive outcome in the scenario, while their supposed "friend and fellow hero" is actually trying to ensure a negative outcome. This ensures challenge for each player without necessitating that the players be targetting each other, limiting the sense of mutual dependence, or requiring that the relationship be entirely based on lies.
In truth, the variance between the heroes and the villain might only a slight difference in ideology, the burden of a dark family secret, or the interplay of noble but misguided intentions.
Example:
*Over time the group learns that an ancient prophecy claims a soul-collecting terror from ages past will rise again to plague a small village on the ancestral lands of one of the characters.
As they uncover more and more about the prophecy, they realize that the time will soon arrive. They must act now. They become desperate to discover a way to prevent or guard against the soul-collector.
Throughout this period, the villain is aware that it was their many times great grandmother which unleashed this foul curse on the village in the first place to spare her own children from the ravages of the soul-collector. If the villain chooses to delve deeper into the lore of the family, they will discover much more about the monster than the heroes, including that it was bound by the family to both stop greater depredations and to extract special favors from it. They can, if they have the will, learn how to bind it, and become tempted by what the being will offer for even a little bit of freedom. They will also learn that if the monster is balked it will come for them, their siblings, and other members of that generation within the family and nothing will be able to stop it. Worse, if they reveal the family secret they will be disowned, the monster will take back all the gifts it provided the family, and it will be set loose to kill indiscriminately. To ice the cake, if the villain chooses to master the rites involved, they can gain direct control of the monster and earn their own, very special favors from it.
The heroes will of course be committed to stopping the creature, and their flawed understanding of the situation will enable the villain, if they stick close to the heroes, to monitor progress and to try to redirect it when necessary to prevent success.*
Requirements
This style of scenario best pits character goal versus character goal, but not character versus character explicitly. It does not need to require that the villain receive lots of useful extra knowledge, nor that they go off for extended periods to plot or take care of things off-screen. Moreover, it allows all the players to play toward a goal of uncertain resolution, rather than forcing one of them to be a glorified NPC just there to trick the players. A great scenario will have lots of conflicting emotions on both sides of the group as the course of events plays out.
Key Points
- Everyone plays in the scenario, no ringers or PCNPCs
- Each has a related goal that they may or may not achieve
- once play starts there is no meta-fiddling with the villain's
knowledge or activities
- the heroes may remain focused on ending the threat little knowing
they have a viper in their midst
- the villain has the burden of keeping their secret agenda of foiling
the goal of the heroes without getting caught
At the end, there is a chance for a dramatic conclusion when the duplicity of the villain ultimately comes to light. If the bonds between all the PCs are tight, the heroes may even be swayed to the villain's side...
Best Answer
Two reasons.
First, the various horrors and Things Man is Not Meant to Know that populate the universe in a Lovecraft Mythos game are not organised enough (against us, at least) to pull this kind of thing off as a regular tactic—if they were, the world would already be consumed, enslaved, or worse. Since we're playing a game where we investigate and try to stop that kind of fate, we can presume that the horrors haven't gotten it together enough, or just haven't bothered yet, to destroy the world. Teleport-bombing is small potatoes: why bother when it's easier to just eat the planet?
Second, they just don't think like people do. What makes sense for us as a sure-fire strategy just doesn't matter to them. It's much like a fly beating at a window (where we are the fly in this analogy and the horrors are the humans): it's obvious to the fly that the solution is to go straight through that unobstructed opening in the wall! Why don't the giant pink creatures that we're fleeing from, which clearly want to eat us, pursue us? We're getting away!
Except the fly isn't getting away, it's trapped. And we don't care. And our motives are certainly not comprehensible by the fly. Also, maybe we're not organised enough to deal with the clear and present danger that this insect poses to… our plans for getting ready for work and finding our keys? Maybe we'll take a half-hearted swipe at it while we go by, but unless the fly swatter is ready to hand we're just going to get on with our day and let the fly die in the window in its own time. A spider (i.e., Shoggoth, etc.) will probably get it for us anyway.
Humanity, and the whole Earth really, is like that fly to the Lovecraftian horrors. They're inimical to us, yeah, just like people really don't like flies in their house. But they're not going to bother with eradicating us unless it's convenient, they usually don't think about us, and the only time they'll actively go after us is when we pretty much fly straight into their "hands". If their incomprehensible cosmic plans call for it, they'll get organised and eradicate us, but why would they bother otherwise? Are you really going to fumigate your house every time a fly gets in? No, you're only going to bother with a major infestation, or when trying to sell the house in a tough market, or something like that. And how much can that fly in the window grasp about these factors that control its fate and continued living? None. It just beats against the glass.
Event that analogy is flawed, because it attempts to parallel their thoughts to ours. The useful take-away part of the analogy is that we're insects to them, not worthy opponents that deserve much attention or efforts to teleport-bomb, and that our intellects and comprehension of what is sensible is so disconnected from the true nature of reality that we can't explain or predict their actions.
The only adversaries in a Mythos setting that are going to be motivated in a human-understandable way enough to want to teleport-bomb the heroes are other humans, and if they're treating with horrors enough to become dangerous cultists, they're already far gone enough that what they're doing is already quite insane and has incomprehensible motives. Insanity is enough explanation to not do the obvious thing.
Even sorcerers who have maintained enough of their cunning to be somewhat comprehensible in their motives are going to have more going on than merely teleport-bombing some annoying investigators. Being Mythos sorcerers, to do anything mystical they have to get close to those horrific truths of reality that can burn out a mind, and how often can someone grab hot coals to fling at their enemies before they get burned? The more powerful the sorcerer, the more frequently they use their power, the more likely they are to have inhuman motives or to provoke or discover something that will destroy them (or the world). Sorcerers are either going to be self-limiting for their own sanity and safety, self-limiting by being insane and doing incomprehensible things for incomprehensible reasons (see above), or they're going to be self-limiting by earning a Darwin Award.