Many modern games are all about the graphics, with the developers exploiting the very latest engines and technologies to deliver some truly cinematic experiences.

Get past the eye candy, though, and there’s not always a great deal left. So if you place a higher value on compelling gameplay, then you might find considerably more entertainment in a retro-style project, something that’s based on interesting ideas rather than just pretty pixels.

OpenRA, for instance, is an open-source implementation of the Red Alert engine, which right now supports classic Westwood games like Command & Conquer and Command & Conquer: Red Alert. These aren’t clones of the originals, rather they’re what the developers call “reimaginings”, with “improved and rebalanced gameplay”.

If you don’t remember the originals, then these are real-time strategy classics, which helped to create the rules which many RTS games still follow today. In a skirmish, for instance, you’ll start with a single base; begin collecting resources to build up your economy; construct base defences, buildings and units; then scour the rest of the map for your enemies, turning every last one to dust with your high-tech weaponry.

You can play against the computer, but there’s also support for multiplayer games played both locally and over the internet, and the authors are constructing a single-player campaign, too.

Graphics? They’re, well, basic. Even by 1990’s standards. We’ve always loved the Command & Conquer series, though, & OpenRA provides a fun and free way to enjoy their engrossing gameplay once more.

If OpenRA’s tiny sprites are just too basic for your tastes, though, you might prefer something like UFO:Alien Invasion. It’s based on a version of the Quake 2 engine, so still isn’t exactly what you’d call leading edge, graphically speaking, but it can look reasonably good. (Although the down side is that all these maps and visuals make for a bulkier download at more than 500MB.)

Gameplay this time is based on the old X-COM PC games, where you control a secret organisation charged with protecting with world from a brutal alien invader.

Some of the game is played at a fairly high level, in Geoscape mode. You’ll build bases, research new technologies to help you in your battles, select and train soldiers, deploy and launch interceptor craft to shoot down invading UFOs.

The heart of the game, though, is Tactical Mode, where you send a hand-picked team of specialist soldiers to an area with reports of alien activity, and have them find out exactly what’s going on.

What’s really interesting here is that this works in a turn-based form. Every soldier has a certain number of “time units” to spend per turn. You might use these to move a soldier as far forward as possible across a map, for instance. But, you may find his very last step brings an alien into his sight. And so when your turn ends, the alien will be able to attack and kill him with ease.

So what you have to do instead, then, is be careful, move forward slowly, don’t rush around blind corners or into rooms unless you know what’s there and other members of the team are available to cover you. Which is, of course, actually quite what this situation would be like in real life. So although the turn-based approach seems primitive, and won’t be to everyone’s tastes, it turns out to be surprisingly good at generating tension and excitement. And if you’re looking for a free game with the depth to keep you engrossed and entertained for quite a few hours, then UFO:Alien Invasion could be a very good choice.