These are all my opinions/feedback on FE. I hope they help the designers of the game (even if you don't follow my ideas to the letter).
I played about 20 hours of WoM, and I'm up to ~120 hours of FE so far. I played one game of vanilla FE, before I got bored and installed Stormworld, which made the game insanely more fun and interesting.
Like Civ 4 (which probably hurts the devs feelings slightly), Stormworld has become the Fall From Heaven of FE for me. The new races and mechanics are wonderful and a very much needed polish that I believe the original game would have benefited from having. If the company isn't actively working with the Stormworld guy, and maybe helping to feed him assets (like models and whatever else he might need), I'd suggest really going out of your way to do that. Stormworld is probably going to sell a ton of copies of FE further down the line, because it's really neat and fun!
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Okay, other main thoughts. Tactical combat is boring. It's fun for a little bit, but then it really starts to get a bit dull. I've read about people asking for backstab, flanking mechanics, etc, and I had a wonderfully elegant implementation that would make combat lots of fun!
Add in 20-30 unique combat SKILLS, like:
Backstab (x2 DMG if an ally flanks target)
Sunder (Reduces a targets defense for 2 rounds. Stacks)
Pikewall (Replaces standard +5 Defense for no action; double defense and infinite counterattacks against units with a higher initiative)
Channeling (In game already, but variations of stacking: reduced mana cost or increased dmg or increased spell mastery)
Prayer, or whatever thematically fits (1 round cast, +2 hp to all allies, no mana cost on use; something for healy types to 'do' every round)
Fortify (Replaces standard +5 Defense; stacking +5 Defense & +1 Counterattack until unit moves or attacks; non-stacking -50% initiative and -1 moves until unit moves or attacks.
Once you add in all these abilities, give EVERY, SINGLE UNIT TYPE one of these abilities WITH A COOLDOWN. Champions start with a single ability (which helps define a path for them from level 1 on); trained units might get something based on weapon type (or trained for additional labor costs); maybe have new abilities unlock at tech levels, but keep it relatively simple and streamlined.
The weapon types already kind of have this (counterattacks, second strikes, chance to knock down, no counterattacks), etc, but these passive bonuses aren't fun. Instead if units have a mesh of abilities that come on/off cooldown, it makes it lots more interesting. Every unit has something special it can do (from lowly scouts to mighty dragons), and they're all more fun an interesting.
This kind of overhaul could be a wonderful selling point for an expansion. The kind of thing that builds on the base of FE and just cements this as a classic.
These revelations came from playing a Beast Lord soveriegn, btw; I had so much more fun playing with the monsters vs. my boring trained troops.
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Second, I kind of feel like the art is lacking a bit, but it doesn't bother me a ton. I play entirely on the cloth map, and the game is very attractive and elegant that way, especially with the grid turned on. my first impressions were that this game was dated by 10-15 years, but after more time on the cloth map, I get a totally different impression. Maybe try to push that a little more as the default (especially with the grid turned on), and you'll make a better first impression. However, after you start playing, it is neat to be able to zoom in on the world and 'see stuff.' Maybe just set the default cloth to art transition a little bit lower.
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Third, a better way to transfer items between champions would rock. Maybe just a kingdom vault anyone can put stuff in or take stuff out of.
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Finally, give us like 20 times more quest/random event content. They seem so simple to create. Even if they're the same monsters, presented in different ways, it's fun and interesting to explore the world. It's such a neat, low-cost vehicle to create content. It seems like you could create new quests in an hour max. Have them continually pop up in the world, over the course of the game. Create 'civilized' quests that pop up later on in civilized lands (rebellions, new allies, etc).
As soon as combat gets that tiny little oomph to make it fun, all this game needs is a steady stream of content and it's set. DLC packs can include new, high quality races (a la Stormworld races with new art and perks and mechanics), new monsters and lairs and quests that are plug-and-play; buy the DLC, and the new content just starts appearing in the game.
Basically, make amazingly wonderful mods for your own game (which you have complete access to in every way), and produce more and more content for it! I could me myself playing FE over a long time with lots of fresh updates!
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Thanks again for reading all this. Loving the game lots!