OpenRA is a Libre/Free Real Time Strategy game engine supporting early Westwood games like Command & Conquer and Command & Conquer: Red Alert.

OpenRA can be currently played as online multiplayer game only. However, you can create a single player game by selecting bots as enemy opponents with three different AIs (easy, medium, hard).

Watching from top, player selects units, and send them around attacking enemies. You also build buildings, and can controls superweapons like nuke and chrome. Naval units like subs and cruisers, and planes and helicopters help balance the gameplay, and has been a little changed from the original games.

If you have original Red Alert files, you can use them with OpenRA. But, they are not necessary. Both original C&C: Red Alert and C&C has been recreated as mods and can be downloaded from game menu itself. They are not just clones of the original versions but provide improved and rebalanced gameplay.

The website of OpenRA offers the open code, a place to report bugs has a forum where gamers can discuss new ideas and modifications they have made or would like to make to the game.

The irc channel #openra on freenode is active, and developers hang out to help modders and mappers make new cool games.

2 new advanced mods have been created, and more are coming. Mappers can also make creative maps with totally different gameplays. The wiki, forum and the irc channel will give you help.

The unstable playtest is the most played, be sure you download that. And ask in Irc if anyone can host a game for you, or invite players to your games..