Used an auto clicker to kill them but that took too much work this will auto kill the Saliens.

1) Login to Steam on Chrome
2) Visit a planet and start the round
3) As soon as the round starts press F12 and paste the following code into the console

CEnemy.prototype.Walk = function(){ this.Damage(1000);}

You may need to paste it a few times for it to kick in but it will auto kill them as they enter the screen.

Once you've ran the code it will always work as long as you don't refresh.

Update:

Sean wrote Tamper Monkey

AutoSelect Planet, Invincibility, InstaKill, auto reload if server is down

// ==UserScript==
// @name             Saliens Hack
// @description     Saliens Hack for Steam Summer Sale 2018 Game - AutoSelect Planet, Invincibility, InstaKill
//
// @author         Cory "mbsurfer" Shaw
// @namespace       http://github.com/coryshaw1
// @downloadURL      https://gist.github.com/coryshaw1/ed51d13baa8191f53f489b9de25cc868/raw/b4807713964a9b67e1b8d7837256845b078a51c6/saliensHack.user.js
//
// @license         GPLv3 - http://www.gnu.org/licenses/gpl-3.0.txt
// @copyright       Copyright (C) 2018, by Cory Shaw
//
// @include         https://steamcommunity.com/saliengame/play/
// @match         https://steamcommunity.com/saliengame/play/
//
// @version         1.0.5
// @updateURL      https://gist.github.com/coryshaw1/ed51d13baa8191f53f489b9de25cc868/raw/b4807713964a9b67e1b8d7837256845b078a51c6/saliensHack.user.js
//
// @run-at         document-start|document-end
// @unwrap
// ==/UserScript==

/**
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * SCRIPT DESCRIPTION.
 *
 * @see http://wiki.greasespot.net/API_reference
 * @see http://wiki.greasespot.net/Metadata_Block
 */
(function() {   
    CEnemy.prototype.Walk = function(){this.Die(true);};
    var joiningZone = false;
    var gameCheck = function(){
        if (!gGame || !gGame.m_State) return;

        if (gGame.m_State instanceof CBootState && gGame.m_State.button) {
            startGame();
            return;
        }

        if (gGame.m_State.m_VictoryScreen || gGame.m_State.m_LevelUpScreen) {
            gGame.ChangeState( new CBattleSelectionState( gGame.m_State.m_PlanetData.id ) );
            console.log('round done');
            return;
        }

        if (gGame.m_State.m_EnemyManager) {
            joiningZone = false;
            return;
        }

        if (gGame.m_State.m_PlanetData && gGame.m_State.m_PlanetData.zones) {
            var uncapturedZones = gGame.m_State.m_PlanetData.zones
                .filter(function(z){ return !z.captured })
                .sort(function(z1, z2){return z2.difficulty - z1.difficulty});
           
            if (uncapturedZones.length == 0) {
                console.log("CHOOSE NEW PLANET. THIS ONE IS DONE.");
                return;
            }

            joinZone(uncapturedZones[0].zone_position);
            return;
        }
    };

    var intervalFunc = setInterval(gameCheck, 100);

    var joinZone = function(zoneId) {
        if (joiningZone) return;
        console.log('Joining zone:', zoneId);

        joiningZone = true;

        clearInterval(intervalFunc);

        gServer.JoinZone(
            zoneId,
            function ( results ) {
                gGame.ChangeState( new CBattleState( gGame.m_State.m_PlanetData, zoneId ) );
            },
            GameLoadError
        );

        setTimeout(function() {
            intervalFunc = setInterval(gameCheck, 100);
        }, 10000);
    };

    var startGame = function() {
        console.log('Pressing Play');

        clearInterval(intervalFunc);

        gGame.m_State.button.click()

        setTimeout(function() {
            intervalFunc = setInterval(gameCheck, 100);
        }, 5000);
    };
})();

Sean wrote Best version of the script fixed server issues and it auto maxes the score

// ==UserScript==
// @name             Saliens Hack
// @description     Saliens Hack for Steam Summer Sale 2018 Game - AutoSelect Planet, Invincibility, InstaKill
//
// @author         Cory "mbsurfer" Shaw
// @namespace       http://github.com/coryshaw1
// @downloadURL      https://github.com/coryshaw1/saliens-hack/raw/master/saliensHack.user.js
//
// @license         MIT License
// @copyright       Copyright (C) 2018, by Cory Shaw
//
// @include         https://steamcommunity.com/saliengame
// @include         https://steamcommunity.com/saliengame/
// @include         https://steamcommunity.com/saliengame/play
// @include         https://steamcommunity.com/saliengame/play/
//
// @version         1.1.2
// @updateURL      https://github.com/coryshaw1/saliens-hack/raw/master/saliensHack.user.js
//
// @run-at         document-start|document-end
//
// @grant           unsafeWindow
//
// @unwrap
// ==/UserScript==

/**
 * MIT License
 *
 * Copyright (c) 2018 Cory Shaw
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

(function() {
    if (typeof unsafeWindow !== "undefined")
       unsafeWindow.requestAnimationFrame = c => { setTimeout(c, 1000 / 60); };

    // Game broke reload and try again
    GameLoadError = function() {
        clearInterval(intervalFunc);
        setTimeout(function() {
            if (typeof unsafeWindow !== "undefined")
                unsafeWindow.location.reload();
            else
                window.location.reload();
        }, 750);
    }

    CEnemy.prototype.Walk = function(){this.Die(true);};
    var joiningZone = false;
    var joiningPlanet = false;
    var gameCheck = function(){

        if (!gGame || !gGame.m_State) return;

        if (gGame.m_State instanceof CBootState && gGame.m_State.button) {
            startGame();
            return;
        }

        if (gGame.m_State instanceof CPlanetSelectionState && gGame.m_State.m_rgPlanets) {
            // Go to uncaptured zone with the higheset difficulty
            var uncapturedPlanets = gGame.m_State.m_rgPlanets
                .filter(function(p){ return p.state && !p.state.captured })
                .sort(function(p1, p2){return p2.state.difficulty - p1.state.difficulty});

            if (uncapturedPlanets.length == 0) {
                console.log("ALL PLANETS ARE DONE. GG.");
                return;
            }

            joinPlanet(uncapturedPlanets[0].id);
            return;
        }

        if (gGame.m_State.m_VictoryScreen || gGame.m_State.m_LevelUpScreen) {
            gGame.ChangeState( new CBattleSelectionState( gGame.m_State.m_PlanetData.id ) );
            console.log('round done');
            return;
        }

   if (gGame.m_State.m_ScoreIncrements && gGame.m_State.m_ScoreIncrements != 0 && gGame.m_State.m_rtBattleStart && gGame.m_State.m_rtBattleEnd) {
      var ptPerSec = (gGame.m_State.m_rtBattleEnd - gGame.m_State.m_rtBattleStart) / 1000;
      gGame.m_State.m_Score = gGame.m_State.m_ScoreIncrements * ptPerSec;
      gGame.m_State.m_ScoreIncrements = 0;
   }

        if (gGame.m_State.m_EnemyManager) {
            joiningZone = false;
            return;
        }

        if (gGame.m_State.m_PlanetData && gGame.m_State.m_PlanetData.zones) {
            joiningPlanet = false;
            // Go to boss in uncaptured zone if there is one
            var bossZone = gGame.m_State.m_PlanetData.zones
                .find(function(z){ return !z.captured && z.boss });

            if (bossZone && bossZone.zone_position) {
                console.log('Boss battle at zone:', bossZone.zone_position);
                joinZone(bossZone.zone_position);
                return;
            }

            // Go to uncaptured zone with the higheset difficulty
            var uncapturedZones = gGame.m_State.m_PlanetData.zones
                .filter(function(z){ return !z.captured })
                .sort(function(z1, z2){return z2.difficulty - z1.difficulty});

            if (uncapturedZones.length == 0 && gGame.m_State.m_PlanetData) {
                console.log("Planet is completely captured.");
                leavePlanet(gGame.m_State.m_PlanetData.id);
                return;
            }

            joinZone(uncapturedZones[0].zone_position);
            return;
        }
    };

    var intervalFunc = setInterval(gameCheck, 100);

    var joinZone = function(zoneId) {
        if (joiningZone) return;
        console.log('Joining zone:', zoneId);

        joiningZone = true;

        clearInterval(intervalFunc);

        gServer.JoinZone(
            zoneId,
            function ( results ) {
                gGame.ChangeState( new CBattleState( gGame.m_State.m_PlanetData, zoneId ) );
            },
            GameLoadError
        );

        setTimeout(function() {
            intervalFunc = setInterval(gameCheck, 100);
        }, 10000);
    };

    var joinPlanet = function(planetId) {
        if (joiningPlanet) return;
        console.log('Joining planet:', planetId);

        joiningPlanet = true;

        clearInterval(intervalFunc);

        gServer.JoinPlanet(
            planetId,
            function ( response ) {
                gGame.ChangeState( new CBattleSelectionState( planetId ) );
            },
            function ( response ) {
                ShowAlertDialog( 'Join Planet Error', 'Failed to join planet.  Please reload your game or try again shortly.' );
            }
        );

        setTimeout(function() {
            intervalFunc = setInterval(gameCheck, 100);
        }, 10000);
    };

    var leavePlanet = function(planetDataId) {

        if (joiningPlanet) return;
        console.log('Leaving planet:', planetDataId);

        joiningPlanet = true;

        clearInterval(intervalFunc);

        gServer.LeaveGameInstance(
         planetDataId,
         function() {
            gGame.ChangeState( new CPlanetSelectionState() );
         }
      );

        setTimeout(function() {
            intervalFunc = setInterval(gameCheck, 100);
        }, 10000);
    };

    var startGame = function() {
        console.log('Pressing Play in 2 seconds');

        clearInterval(intervalFunc);

        // wait 2 seconds for game to load
        // TODO: find a way to do this programmatically
        setTimeout(function() {
            gGame.m_State.button.click();

            setTimeout(function() {
                intervalFunc = setInterval(gameCheck, 100);
            }, 5000);
        }, 2000);
    };
})();