Gameplay
As Lost Souls is a standalone expansion, its gameplay is very similar to that of the previous expansion pack, The Moon Project. The only real difference is that the campaign missions were heavily criticized by fans because the AI adapted from a strategy of constant harassing to heavy ground and air assaults nearly constantly. Most maps can only be won with a war of attrition: the player can fortify his/her position and wait until the AI runs out of resources, at which point it tries to get the player's. If the player can stop this, the AI becomes vulnerable to attack, aside from the frequent reinforcements.
Another major difference in difficulty is that the AI always start with a fully built and heavily fortified base. On Medium difficulty, the computer also gets a main base, just like the player. A major counter to this is that the player neither need to send resources back to the main base for evacuation fleet construction nor work with a time limit. Resources are abundant on each map and unused resources are automatically sent back to the main base's resource pool at the end of the mission.
Compared to the original game, all sides have received new additions to their respective arsenals; namely, the new anti-air weapons, which cannot attack ground units but are extremely effective against aerial ones. These new weapons are: the ED's AA Gun, similar to WW2-era anti-air weapons; the UCS' AA Plasma Cannon, which now explains why aircraft should be equipped with shields; and the LC AA Rocket, the one with the longest range of all.
New artillery weaponry also appears for the ED and UCS. These are most suitable for destroying structures from a very long distance. Although ED had monopoly over long-range nuclear ballistic missiles, they now also have a rapid firing artillery cannon, added in the most recent patch. In addition, both the ED and the UCS now possess submarine units armed with ballistic missiles (nuclear for ED, plasma for UCS). To counter this, the SDI Defense Center building has been upgraded in the patch: it now shoots down not only nuclear missiles, but the UCS Plasma Control Center's plasma bolts as well, resulting in the LC Weather Control Center remaining as the only truly unstoppable superweapon.
Five new chassis types were added: the ED Stealth tank, which is invisible unless its lights are on; the UCS Cargo Salamander, a treaded unit with heavy armor but with the ability to carry the AA Plasma Cannon; the LC Super Fighter, an effective air superiority fighter armed with AA missiles; the LC Fat Girl, a moderately armored unit with four weapon hardpoints; and the LC Tunnel Gouger which removes the factions disadvantage over their inability to modify the terrain without a builder unit. The 2.1 patch also adds a sixth newcomer, the unarmed and very silent Scout helicopter for the ED. This eliminates the disadvantage that ED players couldn't spy on enemy bases because their flying units are all helicopters, which means they are very loud compared to the other factions' aircraft and bound to be noticed by the other player.
Previously, only the ED and the UCS possessed Repairers capable of capturing enemy units and buildings, but only the ED and LC could disable these objects to be captured. The new Grabber is a rebalancing addition, which gives each side a method of capturing enemy buildings without the need to disable them. However, the player can only use a captured production building if it is on the same faction. This means it is impossible, for example, to be with ED and capture an LC Main Base then begin unit production. Finally, each side can now sell buildings and recycle units to receive half of the original price in credits. This way, the player can evacuate/recycle all units and sell every building except the Landing Zone at the end of each mission for maximum resource gain. Coupled with the Grabber, it is actually more beneficial now to leave enemy structures intact, but capture and sell them.
Read more about this topic: Earth 2150: Lost Souls