diff --git a/theatre/core/src/coreExports.ts b/theatre/core/src/coreExports.ts
index 08ccd4d..a21f8e4 100644
--- a/theatre/core/src/coreExports.ts
+++ b/theatre/core/src/coreExports.ts
@@ -10,12 +10,44 @@ import * as types from '@theatre/core/propTypes'
 import {InvalidArgumentError} from '@theatre/shared/utils/errors'
 import {validateName} from '@theatre/shared/utils/sanitizers'
 import userReadableTypeOfValue from '@theatre/shared/utils/userReadableTypeOfValue'
+import deepEqual from 'fast-deep-equal'
 export {types}
 
+/**
+ * Returns a project of the given id, or creates one if it doesn't already exist.
+ *
+ * If @theatre/studio is also loaded, then the state of the project will be managed by the studio.
+ *
+ * Usage:
+ * ```ts
+ * import {getProject} from '@theatre/core'
+ * const config = {} // the config can be empty when starting a new project
+ * const project = getProject("a-unique-id", config)
+ * ```
+ *
+ * Usage with an explicit state:
+ * ```ts
+ * import {getProject} from '@theatre/core'
+ * import state from './saved-state.json'
+ * const config = {state} // here the config contains our saved state
+ * const project = getProject("a-unique-id", config)
+ * ```
+ */
 export function getProject(id: string, config: IProjectConfig = {}): IProject {
   const {...restOfConfig} = config
-  if (projectsSingleton.has(id)) {
-    return projectsSingleton.get(id)!.publicApi
+  const existingProject = projectsSingleton.get(id)
+  if (existingProject) {
+    if (process.env.NODE_ENV !== 'production') {
+      if (!deepEqual(config, existingProject.config)) {
+        throw new Error(
+          `You seem to have called Theatre.getProject("${id}", config) twice, with different config objects. ` +
+            `This is disallowed because changing the config of a project on the fly can lead to hard-to-debug issues.\n\n` +
+            `You can fix this by either calling Theatre.getProject() once per project-id,` +
+            ` or calling it multiple times but with the exact same config.`,
+        )
+      }
+    }
+    return existingProject.publicApi
   }
 
   if (process.env.NODE_ENV !== 'production') {
diff --git a/theatre/core/src/sheetObjects/SheetObject.test.ts b/theatre/core/src/sheetObjects/SheetObject.test.ts
index 162a4d2..a2b3f20 100644
--- a/theatre/core/src/sheetObjects/SheetObject.test.ts
+++ b/theatre/core/src/sheetObjects/SheetObject.test.ts
@@ -91,7 +91,7 @@ describe(`SheetObject`, () => {
       },
     })
 
-    const seq = sheet.publicApi.sequence()
+    const seq = sheet.publicApi.sequence
 
     const objValues = iterateOver(
       prism(() => {
diff --git a/theatre/core/src/sheetObjects/SheetObject.ts b/theatre/core/src/sheetObjects/SheetObject.ts
index b2ef69b..045d754 100644
--- a/theatre/core/src/sheetObjects/SheetObject.ts
+++ b/theatre/core/src/sheetObjects/SheetObject.ts
@@ -1,6 +1,5 @@
 import trackValueAtTime from '@theatre/core/sequences/trackValueAtTime'
 import type Sheet from '@theatre/core/sheets/Sheet'
-import type {SheetObjectConfig} from '@theatre/core/sheets/TheatreSheet'
 import type {SheetObjectAddress} from '@theatre/shared/utils/addresses'
 import deepMergeWithCache from '@theatre/shared/utils/deepMergeWithCache'
 import type {SequenceTrackId} from '@theatre/shared/utils/ids'
@@ -53,17 +52,6 @@ export default class SheetObject implements IdentityDerivationProvider {
     this.publicApi = new TheatreSheetObject(this)
   }
 
-  overrideConfig(
-    nativeObject: unknown,
-    config: SheetObjectConfig<$IntentionalAny>,
-  ) {
-    if (nativeObject !== this.nativeObject) {
-      // @todo
-    }
-
-    this.template.overrideConfig(nativeObject, config)
-  }
-
   getValues(): IDerivation<Pointer<SerializableMap>> {
     return this._cache.get('getValues()', () =>
       prism(() => {
diff --git a/theatre/core/src/sheets/TheatreSheet.ts b/theatre/core/src/sheets/TheatreSheet.ts
index 29ce91f..554a77d 100644
--- a/theatre/core/src/sheets/TheatreSheet.ts
+++ b/theatre/core/src/sheets/TheatreSheet.ts
@@ -10,6 +10,7 @@ import {InvalidArgumentError} from '@theatre/shared/utils/errors'
 import {validateAndSanitiseSlashedPathOrThrow} from '@theatre/shared/utils/slashedPaths'
 import type {$IntentionalAny} from '@theatre/shared/utils/types'
 import userReadableTypeOfValue from '@theatre/shared/utils/userReadableTypeOfValue'
+import deepEqual from 'fast-deep-equal'
 
 export type SheetObjectConfig<
   Props extends PropTypeConfig_Compound<$IntentionalAny>,
@@ -25,7 +26,7 @@ export interface ISheet {
     config: SheetObjectConfig<Props>,
   ): ISheetObject<Props>
 
-  sequence(): ISequence
+  readonly sequence: ISequence
 }
 
 export default class TheatreSheet implements ISheet {
@@ -49,14 +50,21 @@ export default class TheatreSheet implements ISheet {
       `sheet.object("${key}", ...)`,
     )
 
-    // @todo sanitize config
-
     const existingObject = internal.getObject(sanitizedPath)
 
     const nativeObject = null
 
     if (existingObject) {
-      existingObject.overrideConfig(nativeObject, config)
+      if (process.env.NODE_ENV !== 'production') {
+        if (!deepEqual(config, existingObject.template.config)) {
+          throw new Error(
+            `You seem to have called sheet.object("${key}", config) twice, with different values for \`config\`. ` +
+              `This is disallowed because changing the config of an object on the fly would make it difficult to reason about.\n\n` +
+              `You can fix this by either re-using the existing object, or calling sheet.object("${key}", config) with the same config.`,
+          )
+        }
+      }
+
       return existingObject.publicApi as $IntentionalAny
     } else {
       const object = internal.createObject(sanitizedPath, nativeObject, config)
@@ -64,7 +72,7 @@ export default class TheatreSheet implements ISheet {
     }
   }
 
-  sequence(): TheatreSequence {
+  get sequence(): TheatreSequence {
     return privateAPI(this).getSequence().publicApi
   }
 
diff --git a/theatre/package.json b/theatre/package.json
index 095eb35..508b6ed 100644
--- a/theatre/package.json
+++ b/theatre/package.json
@@ -87,5 +87,8 @@
     "typescript": "^4.4.2",
     "url-loader": "^4.1.1",
     "uuid": "^8.3.2"
+  },
+  "dependencies": {
+    "fast-deep-equal": "^3.1.3"
   }
 }
diff --git a/yarn.lock b/yarn.lock
index 6fa9d20..f433b4b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -22697,6 +22697,7 @@ fsevents@^1.2.7:
     esbuild-loader: ^2.13.1
     esbuild-register: ^2.5.0
     exec-loader: ^4.0.0
+    fast-deep-equal: ^3.1.3
     file-loader: ^6.2.0
     fs-extra: ^10.0.0
     html-loader: ^2.1.2