Chen-ChensGradiusMod icon


This mod aims to implement features from classic shoot-em-up games. It contains a fully functional Drone API, fully documented. It also improves behavior and mod compatibility of drones.

Last updated 2 weeks ago
Total downloads 62737
Total rating 11 
Categories Mods Libraries Tweaks Items
Dependency string Chen-ChensGradiusMod-3.4.3
Dependants 19 other mods depend on this mod

This mod requires the following mods to function

bbepis-BepInExPack-5.4.9 icon

Unified BepInEx all-in-one modding pack - plugin framework, detour library

Preferred version: 5.4.9
tristanmcpherson-R2API-3.0.44 icon

A modding API for Risk of Rain 2

Preferred version: 3.0.44
ThinkInvis-TILER2-5.0.1 icon

ThinkInvisible's Library of Extras for RoR2.

Preferred version: 5.0.1
Chen-ChensHelpers-1.0.15 icon

This mod includes helpers that may aid other mod creators. Fully documented, so feel free to check it out.

Preferred version: 1.0.15


License: GPL v3
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RoR2: Chen's Gradius Mod


This mod aims to implement features from the Gradius series as well as from other classic shoot-em-up games. The mod also changes some vanilla aspects of the game regarding drones.

It contains a fully functional Drone API. The documentation can be found in the wiki.


Use Thunderstore Mod Manager to install this mod.

If one does not want to use a mod manager, then get the DLL from Thunderstore.


Gradius' Option
Gradius' Option
- A new Red Item added to Risk of Rain 2. Upon receiving this item, all owned drones of the receiver will gain an Option/Multiple for each stack.
- Gradius is known for its feature of Options/Multiples where in these weapons are invulnerable to all damage, and are able to copy the full arsenal of the main ship.
- For this mod, the Options/Multiples will only copy the main attacks of the drone.
- All vanilla minions (both mechanical and organic) are supported.
- All drones from this mod are also supported.
- Options/Multiples are able to duplicate all attacks of Aurelionite. The Rock Turret will attack faster instead of being copied.
- Options/Multiples will only duplicate the ranged attack of Beetle Guards. Their melee attacks will have multiplied damage, however.
- Equipment Drones will use the attached equipment depending on the number of Options/Multiples it has. This is configurable.
- Documentation is available for other mod creators. Check the wiki.

Gradius' Option Seed
Gradius' Option Seed
- A new Green Item added to Risk of Rain 2. Upon acquiring this item, 2 Option Seeds will spawn for the player. They will duplicate the survivor's attacks for a % of damage dealt.
- The Option Seed is a fragment of the completed version of it. While it is in its younger stage, it is more organic than mechanical.
- Only offensive skills of vanilla survivors can be duplicated.
- The API makes it possible to implement customized skill behavior, even with non-offensive ones.
- Documentation is available for other mod creators with modded survivors. Check the wiki.

Beam Drone
Beam Drone
- A drone powered by this mod's API. Check the wiki on how to add your own custom drone.
- This drone shoots a continuous beam on its target.
- The drone is accurate, however, it is weak at keeping its lock on consistently.
- The drone will appear in Stage 3 and onwards.
- The drone will spawn more in Sky Meadow.
- Options also copy this drone's attacks.

Laser Drone
Laser Drone
- A drone powered by this mod's API. Check the wiki.
- The drone charges for a short amount of time, and then unleashes a strong laser attack, dealing huge amount of damage in an AoE.
- The drone will appear in Stage 3 and onwards.
- The drone will spawn more in Sky Meadow.
- Options also copy this drone's attacks.

Psy Drone Red Psy Drone Green
Psy Drones
- A drone powered by this mod's API. Check the wiki.
- Each drone unleashes strong and unique laser attacks.
- The drones can be bought as one.
- If one of them is destroyed, the other will also be decommissioned.
- Upon being destroyed, the first one to make contact with the map will spawn the interactable again if it is configured to be repurchaseable.
- The drones may appear as soon as in Stage 1, but it is expensive.
- Options also copy each drone's attacks, although not completely.

Artifact of Machines
Artifact of Machines
- An artifact added to Risk of Rain 2. Survivors will have a TC-280 Prototype drone when they spawn. Enemies, however, will also get drones.
- The Bacterian essence has drifted towards the embrace of the Planet. The Bulwark deemed it dangerous, and thus keeping it sealed in an artifact.
- No more drones can be repurchased when this artifact is active.
- When the owner dies, the drones will be decommissioned as well.
- Enemy drones will also have Gradius' Option if the Artifact of Evolution gives the item to the enemy.
- Configure Gradius' Option so that it is not blacklisted.

Other Features

  • Emergency Drone's Null Exception Reference fix. Configurable to be turned off.
  • Allows all drones to be repurchaseable. Configurable each.
  • Allows an Equipment Drone to have a chance to drop its equipment upon being destroyed. Configurable.
  • Makes the Flame Drones spawn more in Abyssal Depths. Config options also offer to allow Flame Drones to spawn more in Scorched Acres.
  • Changes vanilla drone behaviors to be smarter, eliminating the problem of them attacking their own owners as well as widens mod compatibility.
  • Set category of Gunner Turrets as Drones instead of Miscellaneous so that the Director will not spawn too many Gunner Turrets. Configurable.

Contact & Support

More Information

Kirbsuke#0352 made the 3D model for the Option/Multiple, and later used for the icon.
- Contact: or through Discord.

manaboi#4887 helped me edit the icon to make it look like one with vanilla items. Also made Artifact of Machines icon.
- Contact: Through Discord.

KomradeSpectre#8468 made the 3D model for the Beam Drone and Laser Drone, which was also used for their icons.
- Contact: Through Discord.


- Properly apply HGStandrad Shaders to the mod assets. They should look better now.
- Properly add smoke broken effect for each Psy Drone.
- Optimize resource loading.

- Fix a bug in the yellow laser attack of the Green Psy Drone where an exception may occur.
- Fix a bug where as the Green Psy Drone is duplicated upon going to the next stage.

- Implement Arms Race support for Psy Drones.
- Fix a bug regarding double damage in multiplayer.

- Implement Psy Drones, a powerful weapon from a different timeline.
- Allow the other custom drones from this mod to benefit from attack speed bonuses.
- Fix a very bad bug where the Health Components of custom drones aren't properly assigned.
- Actually add a config option for custom drones to be repurchaseable.
- Integrate breaking changes from Chen's Helpers.

- Update the mod so that it works after the breaking changes of Chen's Helpers.
- Implement a new API for a shortcut way to setup custom broken drone models.

For the full changelog, check this wiki page.

Available versions

Please note that the install buttons only work if you have compatible client software installed, such as the Thunderstore Mod Manager. Otherwise use the zip download links instead.

Upload date Version number Downloads Download link  
2021-7-14 3.4.3 4267 Version 3.4.3 Install
2021-7-10 3.4.2 2219 Version 3.4.2 Install
2021-7-8 3.4.1 1104 Version 3.4.1 Install
2021-7-8 3.4.0 34 Version 3.4.0 Install
2021-6-30 3.3.11 2879 Version 3.3.11 Install
2021-6-26 3.3.10 1757 Version 3.3.10 Install
2021-6-25 3.3.9 449 Version 3.3.9 Install
2021-6-21 3.3.8 1952 Version 3.3.8 Install
2021-6-20 3.3.7 567 Version 3.3.7 Install
2021-6-20 3.3.6 147 Version 3.3.6 Install
2021-6-16 3.3.5 1489 Version 3.3.5 Install
2021-6-14 3.3.4 1071 Version 3.3.4 Install
2021-6-13 3.3.3 925 Version 3.3.3 Install
2021-6-12 3.3.2 652 Version 3.3.2 Install
2021-6-11 3.3.1 648 Version 3.3.1 Install
2021-6-11 3.3.0 40 Version 3.3.0 Install
2021-6-4 3.2.0 2154 Version 3.2.0 Install
2021-5-21 3.1.2 3225 Version 3.1.2 Install
2021-5-19 3.1.1 1199 Version 3.1.1 Install
2021-5-17 3.1.0 1759 Version 3.1.0 Install
2021-5-4 3.0.2 2324 Version 3.0.2 Install
2021-5-4 3.0.1 39 Version 3.0.1 Install
2021-5-4 3.0.0 320 Version 3.0.0 Install
2020-12-14 2.2.11 9826 Version 2.2.11 Install
2020-12-13 2.2.10 508 Version 2.2.10 Install
2020-12-12 2.2.9 234 Version 2.2.9 Install
2020-12-12 2.2.8 325 Version 2.2.8 Install
2020-12-11 2.2.7 413 Version 2.2.7 Install
2020-12-8 2.2.6 633 Version 2.2.6 Install
2020-12-5 2.2.5 944 Version 2.2.5 Install
2020-12-1 2.2.4 832 Version 2.2.4 Install
2020-11-30 2.2.3 438 Version 2.2.3 Install
2020-11-29 2.2.2 348 Version 2.2.2 Install
2020-11-29 2.2.1 287 Version 2.2.1 Install
2020-11-28 2.2.0 367 Version 2.2.0 Install
2020-11-20 2.1.4 1187 Version 2.1.4 Install
2020-11-19 2.1.3 380 Version 2.1.3 Install
2020-11-16 2.1.2 771 Version 2.1.2 Install
2020-11-15 2.1.1 3796 Version 2.1.1 Install
2020-11-13 2.1.0 536 Version 2.1.0 Install
2020-11-12 2.0.0 332 Version 2.0.0 Install
2020-10-27 1.7.0 2566 Version 1.7.0 Install
2020-10-24 1.6.4 1553 Version 1.6.4 Install
2020-10-22 1.6.3 568 Version 1.6.3 Install
2020-10-21 1.6.2 395 Version 1.6.2 Install
2020-10-20 1.6.1 383 Version 1.6.1 Install
2020-10-19 1.6.0 197 Version 1.6.0 Install
2020-10-17 1.5.1 652 Version 1.5.1 Install
2020-10-16 1.5.0 564 Version 1.5.0 Install
2020-10-15 1.4.1 323 Version 1.4.1 Install
2020-10-15 1.4.0 65 Version 1.4.0 Install
2020-10-12 1.3.4 849 Version 1.3.4 Install
2020-10-11 1.3.3 586 Version 1.3.3 Install
2020-10-10 1.3.2 96 Version 1.3.2 Install
2020-10-9 1.3.1 563 Version 1.3.1 Install