Motherload by XGen Studios (http://www.xgenstudios.com/play/motherload) distills a complicated 4X game, like Master of Orion, down to two joy-inducing tasks: mining for resources and shopping for stuff.

The core mechanic: Pilot your vehicle by using the arrow keys dig, fly, and avoid long falls with a finite fuel source. There's only one real "level" in the game, and it stretches down your screen for a loooong time. Your drill-enabled vehicle can only dig down so deep and dig up so many pieces of ore before having to return to the surface to sell off the goods and clear some cargo space. The trick is to dig up and sell enough ore to upgrade your ship so that it can dig deeper, carry more loot, and survive longer falls. The initial goal is to rack up ludicrous cash, but a story eventually develops that adds meaning to your loot-lust. This mechanic is similar to the much simpler game Lunar Lander, where the player must gently land a spacecraft on a single non-scrolling screen with limited fuel. You can look at Motherload as either a dramatically toned-down Master of Orion or a trumped-up Lunar Lander!

The skin: A quasi-cartoony space mine with a layer of grit and grime over it. The player character is a futuristic mining vehicle. The only non-player character is a human being (… or is he??).

The feature set:

Possible additional features: Sequel features for Motherload could include:

Alternatively, the sequel could just add new content: more ship upgrades, more ore types, a larger play area, more story sequences, more sound effects and music tracks, and so on. This is what game reviewers can derisively call a MOTS (more-of-the-same) sequel.