Steam is an online game seller/host/repository that vends games through the Steam client, created by VALVe (the makers of Half-Life, Counter-Strike, Portal, Day of Defeat, Team Fortress, Left 4 Dead, and Dota 2). On 8/29/2018 RoM became one of those games.
At launch, the following DLC's were available:
|Package||Steam Wallet||In-Game Diamonds||Notes|
|Welcome Gift||Free||Free||7-Day Flying Rune Disk, 7-Day Blue Note Cavy pet, Gathering Speed, XP & TP Potions, Death Forgiveness|
|Scout Pack||$24.99||1,399 ($41.74)†||Costume, house, Cloud mount, Kitsune pet, Class expansion ticket|
|Dragon Adventure Pack||$59.99||3,499 ($104.4)†||Permanent backpack expansion tickets, Dragon mount, Costume, Puss in Boots, Weapon skin|
|Promotion Package||†||49 ($1.46)†||XP and TP potions and charms|
|Refining Starter Packs||†||79 ($2.36)†||Hammers, Drillers and Refining Gems|
|Adventurer Package||†||99 ($2.95)†||Marking Ink, Transport Runes, Hammers, XP, TP and Death potions|
|Transport Package||†||179 ($5.34)†||Marking Ink, Transport Runes|
† In-Game Item Shop only. 60% off normal price!
Yes, Gameforge is aware that the in-game diamonds price is very high compared to the Steam price. The whole point is to encourage the use of Steam Wallet, and Gameforge bases their valuation of diamonds on the discounted price, not the normal pricing the way we do.
UPDATE: Later that day, the DLC on the RoM Steam page were disabled until some issues can be resolved. We think this means that the price difference between Steam and in-game Item Shop was not intended to be so large and they are fixing it. see this post by Celes.
If you have further questions not answered here, check RoM Joint Forums Steam Frequently-Asked-Questions.