Oh sure, it’s basically been pennies for years, but nothing motivates the merely curious like free-free-free. For that is the case for X-COM: UFO Defense aka UFO: Enemy Unknown, the 1994 alien-bothering strategy game that kicked off a series now made something of a household name by Firaxis’ remakes. Only until tomorrow, though.

The Gollop brothers’ original X-COM is my favourite game of all time, and though I won’t pretend nostalgia doesn’t help me get past the barriers presented by so vintage a title, I am resolute that it still holds up beautifully today. Slower, less predictable, more involved and even more sinister than Firaxis’ streamlined successors, it is a titan of both ambition and execution.

If you’ve resisted because you are morally opposed to spending money on something that runs at a resolution of 640×480, you can now obtain a copy of this icon of PC gaming without spending a penny. The Humble Store is offering the whole thing up for free, in the form of a permanent Steam key, until Wednesday evening (UK time). This leaves one day and eight hours at the time of writing. Hurry, hurry, hurry.

There are no strings as such, it’s just that they’re using this to promote their Humble Monthly Bundle subscription service, which currently features last year’s XCOM 2. But frankly, Mr Shankly, I’m of the opinion that X-COM will keep you so entertained that you won’t need XCOM 2 any time soon.