https://boardgamegeek.com/boardgame/312804/pendulum is real-time worker-placement. It's pretty good and fun, as long as you can trust everyone not to cheat (even by accident), and if you get sand timers that don't quietly stick when you're not looking at them. Warning: The rulebook suggests learning the mechanics via a turn-based "non-real-time" variant which my wife and I actually found more confusing than just jumping right into the sand-timer-based full game. My advice is to jump right in.
https://boardgamegeek.com/boardgame/31481/galaxy-trucker is of course fantastic. But more than 50% of the game is not real-time and, as in several Vlaada Chvatil games (e.g. Dungeon Lords), you have to enjoy kind of watching the game play itself for a while.
Galaxy trucker has a good app and would recommend it both on mobile and in real life. Sidereal Confluence is highly complicated, high investment game that's based on frantic negotiation, I can't recommend it unless you're seriously into games.
Space Alert is silly and fun and cooperative. Everyone also is forced to mention Galaxy Trucker as it’s also silly and fun, but the real time nature is quite isolated, and I prefer interactive games. Trading games like Chinatown and Sidereal Confluence often have real time phases for deal-making, of those two Sidereal is the better game by far but Chinatown is the one you’ll actually play. Finally no real time board game list is complete without Captain Sonar, a hyper-competitive 4v4 game of submarine warfare.
If you consider simultaneous turns as a restrained form of real time, then ‘tabletop moba’ Guards of Atlantis 2 is really quite good.
Space Alert is probably the most highly regarded among board game aficionados, but not the most popular. It's complex and stressful, so not everyone's cup of tea.
The most popular real-time board games are probably Set and Bananagrams.
All three of these games are great, I'd recommend any of them that look appealing to you and that you think you can convince people to play.
Space Alert is indeed realtime. I bought Millennium Blades and made one attempt to play it which didn't go terribly well. Galaxy Trucker, as others have mentioned, is great.
Edit: There's also a star-trek pastiche game with two teams that was big a few years back, I never liked it but people enjoy it, can't remember the name.
In my humble opinion, Space Alert can't be beat. Just prepare to explode a lot; like any good co-op, there's a learning curve. After you get hooked, get the expansion, which comes with an addictive character progression system with achievements (and ridiculously hard threats, for good measure).
I really wish there was a version 2 or something. There are lots of annoying quirks in space Alert which could be improved, like the interceptors which never get used. And the lack of any proper difficulty settings.
I'd love a proper Legacy style version of it. I bought the expansion but it seems to add a lot of complication without enough value.
I searched apparently ‘Space Alert’ is the most popular real time board game? Can anyone vouch or recommend one that is known for being real time?