The Atlantic Accelerator is the final level in the game Syndicate. This game was developed by Bullfrog, and published in 1993 by Electronic Arts, who went on to publish a few more games.
This final level is insane. The mission briefing warns that you are completely outgunned and outmanned, and it finishes with a “good luck” message.
As soon as you enter the map you’re assaulted by enemy syndicates wielding mini guns. You have to pause the game and then frantically select all your agents, put on shields and fight back. It can take more than a few goes to get this right. This video shows how easy it is to be overpowered. Jump forward to about 4:00. Warning, it’s loud!
This video below shows how it’s done. Select all agents and put on shields. Select agent 3, enable panic mode and let him or her take out the nearby enemy with a laser. Mop up the rest with lasers.
An idea I picked up from a comment on that video is using plenty of shields and a flamer (flame thrower). The enemy syndicate stop firing after a certain length of time, which makes mopping them up easy. This worked mostly, but in the end there were two enemies left who refused to stop firing. Cross fire was more effective at reducing the numbers of enemy, however.
I finished this game in the mid-nineties. I bought it a good few years ago on GOG and I finished it again, but this was probably my first play through in a decade. Still a great game after all these years.