Being a god requires just one thing, a worshiper. How many, and how active the worshipers are greatly enhances the god's abilities though. It may be that the god has more influence over a small group of followers, or they may create and destroy planes with a modicum of will.
For players, the journey to godhood can be a long, arduous process requiring dedication across multiple adventures and years of work. It can also be the central tenet of a campaign as players seek to build their religion's prominence across the multiverse, or a way of extending your campaign beyond Level 20.
Being a god grants you a number of abilities that mere mortals cannot hope to emulate. You can also attempt to shape reality and beings in ways that normal people cannot.
All gods have access to these skills and may make checks using them. All god skills are charisma skills. Unlike normal skills, god skills utilize your proficiency bonus when the check deals with your godly portfolio. For instance; a Bless check by a god who has "Fields and Harvests" in their portfolio would add their proficiency bonus when attempting to bless a field of grain, but not when attempting to bless a chariot or weapon.Inspire You inspire one of a variety of emotions amongst your target. Select Heroism, Lust, Joy, or Anger before you roll the check. On a successful check, your target is overcome by the emotion and acts upon it. If the target is a worshiper of yours, you have advantage on the check. Guide Give guidance to a worshiper of yours. On a successful check, you gain insight into possible futures and your worshiper's best path forward. AFter hearing your guidance, they have advantage on checks made to follow your guidance. Lead Push or pull a being to actions they would not take on their own. You do not force them to do anything, but place obstacles in their way to prompt them to act in certain ways. On a successful check, the target has disadvantage on checks made to perform actions that go against your leadership. Frighten Cause fear to take hold in a creature. You learn their weaknesses and exploit them to put thoughts of their fears in their mind. For example; you may lead them to think spiders are swarming around them, or that their friends are conspiring against them. On a successful check the target cowers and follows your will. Punish You poke at your target's most cherished things and learn how to remove or change them. On a successful check, gain advantage on all Sculpt Reality checks related to the target's cherished items for one minute. Sometimes, just the fear of losing a cherished thing can be enough to punish the target. Bless You grant your target a gift or boon from your power. On a success, you may give a portion of your power to the target. You may grant them temporary hit points, wealth, or something else that benefits them. The same is taken from you for as long as you give it. For instance, if you bless a worshiper by granting them one of your class abilities, you cannot use that ability. Curse You place a burden upon your target from your power. On a success, you may use your power to make the target's life more difficult. You may cause them to have disadvantage, lower their hit points, remove their wealth, or something else that is a detriment to them. Condemn You condemn a worshiper to life without you. They are anathema and anytime they seek you out, you can readily grant them the opposite of their request, or a bastardised version of their request. The further a worshiper's behavior is from your ideals, the easier it is for you to condemn them. Redeem You redeem a worshiper from another force. You accept them as one of your worshipers and their deepest requests are easier for you to understand. You have advantage on Bless checks made regarding that worshiper for as long as they remain your worshiper. Commune with Worshipper You may speak with a worshiper openly and readily. If they are seeking you out, you have advantage on the check to commune with them. On a failed check, you can only get a handful of words through, or a simple phrase. On a successful check, you can appear to them and carry on an extended conversation. Sculpt Reality The skill needed to make miracles occur. The change can be as simple as changing the color of a cup or as extreme as removing an entire world from existence and history. On a successful Sculpt Reality check, your charisma changes reality to suit your wishes. Not all of these acts are considered miracles though.
Being a god means the faith of your followers has granted you access to special abilities and powers. You gain access to an Indomitable feat at God Level 5 and to an Unending feat at God Level 7. Your DM may choose to limit feats to ones that fit your alignment or portfolio.
Bringing worshipers to your temples and shrines is wonderful, but without a religion for them to practice, it is meaningless. Your actions as a god dictate what type of worshipers you attract, the prayers they make to you, and what sort of abilities their belief grants you.Building a Portfolio
Your portfolio dictates what your proficiency bonus applies to when attempting miracles or God Skill checks. These vary but are most easily figured out through gameplay and role-playing. Your acts of godly prowess and character class can also help influence your portfolio. A druid is more likely to be a god of the forest than a fighter for example. There are no hard limits though, so if the fighter's Acts of Godly Prowess are linked to the forest, they may be a god of the forest.Acts of Godly Prowess
These actions highlight your godly abilities for your followers. They may be real, legend, or real actions mistaken for those of legend. It's rare to plan an act of godly prowess though. Often, such actions occur naturally and are identified after they occur. For instance, players besting a dragon in combat without taking damage may be an act of godly prowess. Likewise, resurrection spells may be misconstrued by worshipers unfamiliar with magic.Miracles
Miracles demonstrate a god's powers by shaping reality into something fitting their whims. To create a miracle, players describe a change to reality they want to make and the DM determines the proper DC for a Sculpt Reality check. Generally, a miracle should be at least DC 35 in order to reflect the impossibility of the task at hand. Something like turning all water in a room into wine, raising a corpse to life, regrowing an amputated limb, or calming a storm would readily constitute a miracle. For every twenty followers witnessing the miracle, the DC reduces by one.
Followers and worshipers provide the lifeblood for your religion, sometimes literally. It is their collective faith that grants you your powers and ability to shape reality. Worshipers need not worship you alone. You may be part of a pantheon, or just worshiped at the times your skills are needed. It only matters that a worshiper believes you are able to grant aid through their worship of you.
While the idea that worshipers primarily seek aid may lead to easier godhood for good, or neutral, characters, evil characters can still become gods. Their worshipers will likely pray for selfish reasons though. A character who constantly steals and cheats their way through life may become a god of trickery and deceit for instance. Their worshipers could then pray to them for help with a con or heist.Shrines & Temples
Worshipers need a place to worship. Shrines sprinkled across the countryside grant travelers with a place to practice your rites. As you grow shrines will give way to temples with edifices of you and clergy of their own. What these look like and are made of varies according to your believers. Gods of nature may have temples built of living wood sculpted into spires, while a god of the mines may have temples built of obsidian or marble blocks.