Playstyle: You start with the highest yield regions in the game, but not terribly many of them. Furthermore, your military is made up of low damage, low HP, low armor conscripts at start. Your army will have plenty of basic units, but lacks powerful high end units. Use your superior wealth to mass troops to your cause and hire mercenaries. You will need their strength to overcome the tougher enemies being sent at you. Two forces will likely make you their target: the Gohma and the Gorons. If the Gohma attack, request the aid of the Kingdom of Hyrule. If they are unable or unwilling to help, then hunker down and fight at the northern choke. At this point, the Gohma should not have heavy units. Keeping the swarm contained will be your top priority. In a war of attrition, you will win. The Gohma can counter this tactic by sending troops through the south by way of Vigjaro. If the Kingdom of Hyrule lets them cross this territory though, they certainly aren't doing their jobs. Make full use of your mercenaries in an attempt to hold the Gohma if this should come to pass. Likewise, if the Gorons attack, send for the aid of the Zora Dominion. Their main goal is to defeat the Gorons, and it will not go well for them if the Gorons claim the high-yield Lanayru territories. If for whatever reason Dominion aid does not come (in which case, I would have serious doubts about the competence of the Zora player), then Coralmold archers will be your best bet against most Goron soldiers. The archers are high-damage, but relatively short range for archers. Luckily for you, the slow speed of the Gorons means an effective micro could be used to great effect. If your allies prove themselves to be incompetent, it may be best to remove them to gain more power for yourself. Only then can you stand on equal footing with your true enemies. WARNING: Lanayru is a difficult race to play as effectively. It is meant to be played by experts only. Novices will likely be overrun quickly.
Evolutions:
Waves of Renewal: Life is difficult for Lanayru Province. Their army is a militia, and they are flanked by two very powerful races. If the Kingdom of Hyrule isn't pulling their weight, than you may be forced to pull of a desparate gambit. Bringing Rutela to the remains of Hyrule Castle will upgrade your Conscripts, Coralmold Archers, and Shore Riders into professional grade troops. In order to gain more powerful troops, you will need to stab your ally in the back, effectively causing their destruction. Timing of the attack is critical. Strike when they are distracted and when you have a large enough force for a successful raid. Beware of retaliation. This is a risky maneuver; but if it works, it can turn the tides in your favor.
Purified Domain: In a similar vein, the Zora Dominion provides another target. Reaching Zora's Domain will be more difficult than reaching Castle Town, but will bear less consequence for failure, as the retaliation capability of the Zora is more limited. Bringing Rutela to the remains of Zora's Domain will grant you more powerful Aurodas, Battle Crabs, and Archer Battle Crabs. If you attack the Zora, a full invasion is recommended. Taking all of the Zora Dominion lands will give you the income necessary to requisition these high-end troops, thus allowing this evolution to gain full effect. This is a contrasting tactic with the single-priority strike force the previous evolution calls for. As such, it is best to determine your army's strengths when picking which ally to betray first. Once you betray one ally, the other may catch on very quickly. Do not fail in your first assault. Otherwise, you will have more enemies, less troops, and no benefit to show for your efforts.
Total Unity: When both of the previous evolutions are fulfilled, a syncratic Hylian-Zora kingdom under the banner of Lanayru will be formed. By utilizing new forging techniques that mix Hylian steel and Zora coralmold, two new levels of weapons and armor may be researched. The Spirit of Lanayru itself will also appear to aid you at this time. If you have reached this evolution, then you are at the height of your power. Make effective use of your armies and eliminate the Gorons and Gohma (if you have not already) then steamroll your way through the south. Since "Waves of Renewal", "Purified Domain", and "Total Unit" are extensions of Lanayru gameplay, I will not give further explanation of these evolutions at a later date.
Rivers Rising: If you are defeated and Airu lies in ruins, the River Zora will emerge to claim the riches of Lanayru and other places. River Zora armies will spawn, scattered throughout Hyrule. Either consolidate your forces or attempt to spread from each point. You will have a limited tech tree and construction capability at this time, but all of your units begin with the "pillage" ability, making raids against poorly defended outposts very profitable. This may be upgraded so that units gain gold for attacking enemy units as well. Ultimately, your goal should be to take Lanayru Province in order to unlock the next evolution. Do not be afraid to pick off unsuspecting enemies like Labrynna, however. Cash is king. Use it well.
Raider Supremacy: If you control all the regions of Lanayru Province and bring Princess Sokuuf to the remains of Airu, a new River Zora kingdom will be established. This will unlock the tech tree, allowing for full construction and recruitment capabilities. In addition, you will be able to form alliances at this stage. A more detailed playstyle for River Zora will be given in the future.