Before there were video games, there were tabletop games. And tabletop games are still a going concern, from classics such as chess or Clue to more recent hits like Arkham Horror or Twilight Imperium. There's a tradition of tabletop games being translated into video game format (and a more recent tradition of video games being translated to board games), but even so, there are a number of games out there which have yet to make the leap. This particular list suggests titles which are deserving of full adaptations into standalone games, not merely duplications for Tabletop Simulator.
So, in no particular order...
1. Cards Against Humanity
You might think this one would be incredibly difficult to pull off, despite being mechanically very simple. It's a game which is inherently a "local" multiplayer sort of enterprise. However, one could look to the Jack Box series of games for inspiration. By using players' smartphones to hide the cards they have been dealt as well as voting for the best player in the round, it wouldn't take quite as much effort actually set up or manage. Even player customization through the use of the "blank" cards would be entirely doable, and far less permanent. Considering the number of expansions that the game has received, it would likely be a game with a small file footprint given that the animations and text would be comparatively small no matter how big or black the box would be.
2. Car Wars
This one is cheating just a teensy bit, since an adaptation was released back in 1985, titled Autoduel (and had Richard "Lord British" Garriott doing some of the design work). That said, it's been 35 years and there's been no modern adaptation since. Electronic Arts had the rights only because they bought up Origin Systems way back when, and the rights have since reverted to Steve Jackson Games. Steve Jackson himself put out a call to any former devs from Origin who might have worked on the game and had the original source code handy, or if there was somebody who still had a copy of the game on floppy discs which could potentially be decompiled. So, there is interest from the creator to bring it to a video game format even as recently as a couple years ago. The obvious and easy adaptation would be along the lines of Grand Theft Auto or Mad Max. A slightly less obvious choice, which would preserve some of the more tactical elements of the game, would be to treat it more like XCOM, allowing difficult maneuvers to be selected from a menu of potential actions.
3. Betrayal At House On The Hill
Horror themes in board games were a very big thing a few years after the Millennium, and no game typifies this better than Betrayal at House on The Hill. Released under the Avalon Hill label, the game uses cardboard tiles in a "roguelike" fashion to create a creepy haunted house which a group of paranormal investigators must move through and investigate, picking up strange artifacts, and facing tests of their bodies and their minds. Eventually, the game shifts to a "Haunt" phase where one player turns traitor (the titular "betrayal") and tries to eliminate the other players. Because the layout of the house is always randomized, and because the nature of the Haunt can always change, it'd be very easy to adapt for a video game, and it would certainly work both as a multiplayer game as well as a single player game. Players could be briefed on their respective roles individually when the Haunt phase starts, ensuring that nobody knows who's friend or foe until it's too late.
Of all the card based games out there, one of the oddest would have to be SPANC. Designed by Fade Manley, and illustrated by Girl Genius creator Phil Foglio, SPANC puts players in the role of a Space Pirate Amazon Ninja Catgirl, cruising the spaceways and embarking on Capers to obtain Toys, Loot, and the occasional Poolboy. Each Caper has certain tests against one or more of a Captain's attributes, and succeeding against a test you might normally be weak against is part of the thrill. As a straight adaptation, it might be a little difficult to pull off, but it would likely allow for a far more colorful experience, potentially evoking a Dragon's Lair-type vibe if the budget allowed for animated vignettes.
5. Twilight Imperium
4X games are nothing new to gamers, tabletop or computer. Yet there are certain brands which seem to be exclusive to the different communities. Stellaris and Master of Orion are the names most recognizable to the PC crowd, while tabletop gamers have Twilight Imperium. Now in its fourth edition, Twilight Imperium is (much like interstellar space itself) big. Really big. The box is big, a single game can take up most of a day going from start to finish, and the amount of potential actions players can take is astounding. Honestly, it's kind of a surprise that nobody's tried to adapt it to a video game. The various mechanics, properly translated on to the computer, could potentially make for a faster paced game than those currently out there. Although 4X games on the PC aren't always short by any stretch of the imagination.
6. Arkham Horror
Probably the hardest sub-genre to pull off in gaming, tabletop or otherwise, is Lovecraftian-style cosmic horror. On the one hand, you're trying to create the right tone of the period. On the other hand, you as a player know that the game is inherently trying to drive your alter ego into gibbering madness. Arkham Horror manages to balance this particular tension nicely. At the same time, it tends to run into the same difficulties as Cards Against Humanity, and for much the same reasons. A video game adaptation would be able to neatly manage expansion content while working to increase the player's immersion in the setting.
7. King of Tokyo
Richard Garfield is well known for creating Magic: The Gathering. But it's not the only game he's done. King of Tokyo, at its core, combines the basic conceit of the classic arcade game Rampage with the dice mechanics of Yahtzee. Players pick a cartoony kaiju, play certain cards and roll dice to see how much damage they're doing to the city or to other players. Some people might be understandably leery about rolling virtual dice, afraid that the RNG mechanics could be poorly optimized. But using a physics-based dice roller would neatly take care of that. And, much like SPANC, the opportunity to visualize "kawaiiju" cheerfully destroying a major city could be attractive to gamers who want a little whimsy to counteract the grim and photorealistic.
No, not the Ghost Recon one. This game from Martin Wallace has been described as "Command & Conquer, but fantasy." Players take control of a fantasy faction and must strike the optimum balance between attack and defense by playing various cards at the right times. Attack too much, and you'll overextend, leaving yourself open to counterattack. Defend too much, and your opponents will wear you down. If an adaptation could evoke the same pulse raising speed of something like Command & Conquer without the carpal tunnel inducing clicks, it could be an excellent game to have on the PC.
9. Lord of The Rings: Journeys In Middle-Earth
This one is somewhat "on the line" only because the board game (released by Fantasy Flight Games) also requires a companion app. You have small elements of gameplay handled by the app, but the actual laying out of the map tiles, drawing of cards, and moving of miniatures is handled manually. It's somewhat baffling that somebody didn't just go whole hog and make a video game version right alongside the board game. The good news is that the elements currently present in the companion app could very easily help speed up production of the video game version.
10. The Quest For El Dorado
This one combines deck building attributes with random map layout elements as players race through jungle depths and across rivers to be the first to reach El Dorado. The cards you use, as well as the ones you buy, determine your strategy. But they can also be an impediment if you pick the wrong cards. The fact that it's a deck building game would also be a bonus due to not having to worry about dice rolls.