Tabletop Simulator is a gaming platform program that allows you to play almost any of your favorite PnP and board games online using your computer. The program also allows for VR functionality. Here are some "ready to play" games available on TTS: (games marked with an *asterisk* are "scripted" which helps players automate certain mechanics) Collectible Card Games Battletech CCG Game Rules Magic The Gathering Deck Building Guide Physics-based Games Tabletop Mini Golf* Quickplay Strategy Games Fallout: New California* Gorechosen (a WH40k-themed game) Portal: The Uncooperative Cake Acquisition Game* The Resistance* Settlers of Catan* Star Wars: Imperial Assault* Star Wars: Legion* World of Warcraft: The Boardgame* Wargames Battletech: Alpha Strike Quick Start Rules Classic Battletech Quick Start Rules (for advanced or Coop play, it is highly recommended you use the Megamek client instead)
Table top Mechwarrior. Admin edit: this has a good number of Battletech assets that could be useful to incorporate, but for an up-to-date and fully contained game, see the updated links in the OP. Either way, thanks for adding this, Solo.
To be clear for those who don't know, that link is for "Classic Battletech". "Mechwarrior" on tabletop is the character-based (more D&D-like) RPG game. Battletech is the more tactical-based version of the game (which the entire franchise is originally based on). If you are going to play classic Battletech, I would still recommend Megamek over TTS because Megamek does all the hard calculations for you. However, if you plan to play the Alpha Strike version of Battletech (which is basically a faster, more streamlined version of the game), TTS is perfect for it.
Here's a quick demo of Alpha Strike in action. It is specifically designed for faster play and being more friendly to new/casual players. I haven't played it, personally, but I'm eager to try it. It would be VERY easy to implement in TTS.