# Collision between two 2D objects.
**URL:** https://discussions.unity.com/t/collision-between-two-2d-objects/206311
**Category:** Questions & Answers
**Created:** [April 6, 2018, 1:19pm UTC](https://discussions.unity.com/t/collision-between-two-2d-objects/206311 "2018-04-06T13:19:08Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Bong\_Sao](https://discussions.unity.com/u/Bong_Sao)
#### Post date: [April 6, 2018, 1:19pm UTC](https://discussions.unity.com/t/collision-between-two-2d-objects/206311/1 "2018-04-06T13:19:08Z")
I’m trying to create a very simple game and am attempting to add collision detection between 2D objects.
I’ve got a space ship, an enemy and a bullet.
I click, a bullet appears, hits the enemy - but I can’t get anything to actually happen.
All the objects have a RigidBody2D attached and a polygon collider.
The collider has “Is Trigger” ticked.
I don’t want any of the RigidBody physics to impact the objects - so I’ve turned off “Simulated”.
In my script for the bullet and the enemy I have:
`private void OnTriggerEnter(Collider other) { Debug.Log("Is triggered"); } `
I’ve tried just about every combination of dynamic/kinematic/use full kinematic contact/IsSimulated and don’t seem to be seeing any difference.
What am I missing - why am I never triggering anything?
---
### Author:  [@Bong\_Sao](https://discussions.unity.com/u/Bong_Sao)
#### Post date: [April 6, 2018, 11:52pm UTC](https://discussions.unity.com/t/collision-between-two-2d-objects/206311/2 "2018-04-06T23:52:38Z")
It actually triggers the following:
```
private void OnTriggerEnter2D(Collider2D other)
```
Subtle but important difference…