What would be nice is if anyone who has played the entire series could go through each game systematically and say what changed in each, how each successor improved upon the previous game (or didn't), as well as any potential story spoilers in later games for the earlier games.
Help me play this series properly.
First. Don't try to bruteforce all of them in a single playthrough. Mechanics evolve in each installment, but the basics are rather similar and you could get burnt out before reaching completion. Geneforge games can be played even as single games, as the basics are always introduced again in every game and the situation is often self contained. But let's see:
+ Geneforge 1: the first. From a mechanical point of view, it's the simplest one, with the most basic ruleset (but after all, you are not playing this for combat) and the less variety in summons/spells. Some encounters are not
that well designed (AUGMENTED SHOLAI
HUmGHHHhhhhHH) and there are some areas that are kind of unnerving. Don't try the Tombs is you don't know what you are doing. Interface is puke green. Writing is quite good, and the atmosphere is one of discovering something abandoned long ago. Factional choice is good, with many actors that you can support, I think the factions are five (three servile sects, Sholai, and *spoilers*). It's basic yet good. If you can stand the interface and some annoying combats, it's a great start.
+ Geneforge 2: Geneforge 1, expanded. Bigger map. More variety in factions, encounters and choices. It's my favourite for player freedom and background, as there is quite a big variety on playstyle (it's the first GF where Canisters become important and have a direct impact on your character). The mechanics and the summon/spell selection is not bigger than GF 1, but the encounter design and the overall writing is far more refined. It's the first GF I have finished, and I recommend it wholeheartedly.
+Geneforge 3: Vogel tried to experiment. Let's start with mechanics. More spells, item creation, two companions (adequately written, derivative but not biowarean bad). Vogel tried to implement a "hub" structure with islands (connected by
fuckin boats, how I hated the boats), where you have self-contained islands that you explore and "complete". It's not
quite successful, but it avoids mindlessly repeating GF1&2. This gave him a bit more
materiel on which to build interesting situations, characters and quests. The downside is that the factional choice is cut down to two. It is the
weakest GF, but still good. Faction leaders on the Shaper side are not *sociopaths*, you have even an happy married couple! Indeed a rare thing in an RPG
+Geneforge 4: GF 3, refined. The *hub* structure is there, but it's modified in self contained "chapters" in the, that put up a main quest to solve and let yout character roam and act. From a mechanical point of view, you get the first great expansion of classes&summons, item forging is expanded and you start not as a shaper but as a Rebel, with some new class choices. The writing is good, despite the fact that the factions are again only two. But this time you start on the other side (Vogel loves this, he did similarly with the Avernum series). You can do some very nice backstabbing and doublecrossing (The Swamps of Monarch are a little jewel in this regard), that you could not do in GF3.
+Geneforge 5: Bigger. Almost adequate graphics. Summons&spells/mechanics are not that different from GF4. Factional choice with multiple options (no longer the Shaper vs Rebels dichotomia that ruled GF3&4). Encounter design is varied, and the game is quite self-contained. I found it the weakest one, but maybe it's because this time I failed to find a faction that truly appealed to me. There are some very good combats, both atmospherical (despite the graphics) and well-designed (despite the limited ruleset). GF 2 has far better C&C, I disagree with Traveler.
If you have to play only one, go for GF 1 or 5. If you want to play more, GF2 is good as an expansion. GF3&4 are both nice games, but they are not the best starting point.
Do you need anything else? Here at your service. I love the GF series. SHAPER POWAH
EDIT: As about story spoilers, Vogel went for a rational choice. You can't convert saves, but there is a canon ending in each game. The best case of this is without doubt GF5, that takes a very interesting approach by keeping one of GF 4's possible endings. And it's quite funny to see how characters (and their priorities and ideas) change, and how the
image of some of the dead ones is employed in later games.
EDIT 2:
why the fuck we have a Spiderweb subforum, what the heck, talk about useless