The concept of OGame is straight-forward: dominate within your initial Solar System, next within your home Galaxy, and finally expand to dominate other galaxies. While doing all of this understand other players are trying to stop you from developing the resources and abilities needed to successfully survive. There are two primary ways to play: as a fleeter/attacker (one who develops ships and the technologies to farm/attack other players and use their resources to expand your own efforts) or as a turtle/miner (one who develops the mining levels and defensive structures needed to defend against fleeters who are seemingly always trying to take your resources.)
As described by the Points system fleeters typically make points faster than miners (primarily because fleeters get 1 point for every ship they build regardless of type: 1 point per Battleship or 1 point for a espionage probe -- both are worth 1 point.)
While there are many variations on these two primary themes the end result is the same: Kill or be Killed. This more true of those players that go idle for weeks at a time. If you are not planning on playing for longer than 7 days it may prove beneficial to enter VMode for the duration - otherwise your planets are subject to attack by anyone regardless of rank (Idle planets are not subject to Noob-versus-Stronger player rules -- even if the noob has just started playing and the target is a planet whose owner has 12,000 points already; if their planets are listed as idle those planets are fair targets.)
Some Game Operators are more likely to clean up 'stale' accounts than others. For example I have noticed on the .Org server there are many accounts that are in the status (i I) and have been for months -- these planets get farmed pretty regularly. But on the .Us server the Game Operators seem to delete these stale* accounts.